-Oliver Cowie, head of humanities at the International School of Chelsea.

His wife, Lyn, found him when she got up this morning.

-Got a neighbor across the road said he saw a push-bike leaning on the wall here last night around 9:00.

-There was no sign of forced entry, Mrs.

Cowie.

It looks like your husband let his attacker in.

So, you'd notice if anything were missing?

-He was backing me in a formal complaint about James Green.

Sexual harassment.

-I wouldn't want the man dead, for God's sake!

I just wanted to protect my thus far unblemished record from a personal vendetta.

-I lied because I didn't want Flo knowing I was unhappy!

-I hate him, Petal.

-"Drop dead, Cowie."

Why would Mr.

Cowie risk his professional reputation to stitch you up, Eric?

-I got back with his daughter.

-Rory Fisk.

-Of course.

-Cowie's been giving him money.

-Giving or paying?

-It would be a good idea if we just kept our distance, just until things blow over, okay?

♪♪ ♪♪ ♪♪ -[ Sighs ] ♪♪ ♪♪ [ Mid-tempo piano music plays ] ♪♪ ♪♪ ♪♪ -Hey, do I have time for a run before you go?

-Not a chance.

-But you're still working.

-Because I had to put Poppy down.

-Oh, I'm sorry.

-Just let me finish this report.

It's nearly done.

[ Baby fusses ] Oh!

See?

She won't settle.

It's like she's knows I'm up against it.

-I'll go check on her.

♪♪ ♪♪ ♪♪ -Boom.

Lyn and her lawyer pal, just where they said they were.

-Nice one.

[ Cellphone chimes ] -Oh.

That's my cab.

Do you want a lift?

-No, thanks.

I'm gonna crack on here.

How come the cab?

-Helen gets back from her mate's hen do tonight.

-And you've trashed the place?

-[ Gasps ] I'm picking up some flowers and a bottle to welcome her home.

-Okay.

-And I've trashed the place.

-Night.

Right.

♪♪ ♪♪ -Looks like we both had a day of it.

-At least you had some adult company.

-You want to talk about it?

-Oh, I just want to go to the pub.

-Don't we all.

-Priya, these are potential clients.

And even if they weren't... -I'm sorry.

Sorry.

-...it's not all about you.

-Okay.

-No, I'm sorry, I'm... I do need... -I know.

I know.

I get it.

Go!

Let your hair down.

♪♪ And don't slam the -- -No, okay.

♪♪ ♪♪ -Do you think he felt it, Mum?

Do you think it hurt?

I can't stop thinking... did he see who did it?

Did he know what was about to happen?

Was he scared?

-He didn't know anything.

He couldn't have.

It would have been over in an instant, I promise you.

♪♪ ♪♪ ♪♪ ♪♪ [ Cellphone rings ] -Don't you ever stop working?

-You'll be glad I didn't when you check your in-box.

-I'm just looking now.

It's downloading.

Where did you get this?

-It was e-mailed to Cowie's work account two weeks ago.

Sender encrypted.

By an amateur.

♪♪ ♪♪ ♪♪ -Got him.

-Good.

We know you sent this photo to Oliver Cowie three weeks ago today.

Is it common behavior for teachers to take secret photos of the pupils in their care?

-Well, obviously not.

It looks a little off.

I can see that.

-Yes, it does.

-It was a spur-of-the-moment thing.

They were in the art department while the rest of their year was in assembly.

And I saw them through the stairwell door.

I was gonna haul them out.

And then I thought, well, it would mean exclusion for Flo.

I was going to delete it as soon as I took it.

-But you didn't.

In fact, you used this photo as leverage against her father.

-Oliver was threatening my entire career for little more than hearsay.

I might never work again.

My whole life would be affected.

So I asked him to drop his vendetta against me in exchange for turning a blind eye.

-And how did that go down?

-He declined.

You don't understand.

I tried to reason with him.

He wouldn't listen.

-So, in Brussels you found out the formal complaint against you had gone ahead, even though Oliver had this photo on his laptop.

So you were hoping he couldn't find out you'd sent it.

But maybe he could.

-Didn't take us long.

Right?

-Right.

So you jumped on an earlier Eurostar -- -Everything else I told you is true -- except... That's what I was looking for in his office.

In case he'd kept a hard copy.

Look, it sounds worse than it is.

-Blackmail, concealing evidence, taking unlawful images of juveniles.

How much worse does it need to be?

-Does this have to go before the board?

-[ Chuckles ] I think the school board is the least of your problems, mate.

♪♪ ♪♪ [ Doorbell rings ] -Morning.

-Oh, hello.

-Is Mrs.

Cowie home?

-She went to solicitors.

There's a lot to sort out, as you can imagine.

Come in.

She said she'd hurry.

She didn't want to leave Flo alone too long.

But Flo insisted on going to school.

I couldn't stop her.

She needs her friends, I suppose.

Would you like a cup of tea?

I just boiled the kettle.

-Oh, yeah.

Tea would be lovely.

-I've been stocking up the freezer for them, bless.

-They're lucky to have you.

Four years, was it?

-On contract.

Paid sick leave, holidays, the lot.

Ask 'round who else gets that who ain't working for a firm.

-They must really rate you.

-Well, trust begets trust, I suppose.

-Must have been a bit of a slap in the face, then.

Uh, the move to Japan, I mean.

Must have been a blow.

-That's life.

I had something else lined up.

-I'd have thought Mrs.

Cowie would need you more than ever now.

-Lyn knows I'm here for her.

[ Door opens ] -I got your message about Flo.

-She wouldn't be stopped, Lyn.

-Maybe it's best.

I don't -- -Lyn.

Police are here.

In the kitchen.

-Okay.

♪♪ ♪♪ DS Shamsie.

-May we speak privately?

♪♪ [ Bell ringing ] ♪♪ -Flo!

-Are you following me?

-They've got my phone, Flo.

I'm so sorry.

-I don't want to talk to you.

-The police have been all over me.

-Don't you dare tell anyone about us.

It won't change anything now.

-I just want to make this okay.

-Then leave me alone, Eric.

I can't stand to look at you!

♪♪ ♪♪ ♪♪ -I knew nothing about this.

-It won't be the first time you've lied to us, Lyn.

-Don't you think I would have said if I knew that vile man was blackmailing us?!

He could be the one who murdered Oliver!

For God's sake!

It was him, right?

-We're talking to Mr.

Green.

And if there's a link, we'll tell you.

-[ Scoffs ] Oliver told me he'd caught Flo and Eric with some vodka.

That's why he banned Eric from the house.

-Maybe your husband was trying to protect you.

-That explains why he was so... rigid.

He wouldn't even consider letting Flo stay with Petal for her final year.

-And you disagreed?

-Flo was kicking off because we moved her around so much.

But underneath, she just needed a bit of leeway to get through the next year without ruining her future.

Because Oliver's future always came first.

So, you see, it wasn't just Saskia we were rowing about.

Oliver thought the move would solve everything.

I didn't.

-Okay.

♪♪ -Everything fits if it weren't for his alibi at the pub.

-Maybe he did just buy a pint and go.

I mean, he's no stranger to manipulating evidence.

-He's not very good at it, though, is he?

-And he was bricking it when we put the pressure on.

I think he would have cracked.

-So, what else have we got?

Despite the spider signatures, I don't believe the kid that painted that painted the first one.

So maybe Cowie did set him up to get rid of him.

-Why would he?

-To protect his daughter?

-He could hardly punish Eric for the coke since Flo was just as guilty.

He needed something to fit him up with.

-It seems pretty juvenile and unprofessional.

Wasn't there a witness, Eric said?

-Yes.

Give the school a call and check with pastoral care.

-Hah!

There's a guy in reception.

Says he's a neighbor of the victim, might have some information.

Ranjit Johal.

He wasn't on the list in the vicinity, so I don't know if he's just a busybody.

-I live half a mile away, but I recognized him from the paper.

I've seen him when I walk my dog.

-So you recognized Mr.

Cowie getting home from work or through the window?

-No, Officer.

I saw him when he answered the door to a man.

-Can you describe the man?

-His back was turned, I'm afraid.

But he was tall, a white man.

I could see his neck because he had very short hair, and he was wearing running clothes.

It was too dark to tell the color of the sweatshirt, but it had a cross on it, like a first-aid sign, a plus sign?

-Like a paramedic or a doctor?

-No, not like that, just a sweatshirt.

And he was annoyed.

Gesturing, you know?

Well, it seemed so, anyway.

Sorry.

-You're being very helpful, Mr.

Johal.

Did you notice a bicycle leaning against the wall?

Or did you get the impression the man had cycled there?

-I thought he had been jogging.

I didn't see a bicycle.

-Do you recall what time this was?

-I always walk my dog at the same time, listening to the radio.

It was just coming up to my favorite program, just before 9:00.

So maybe 10 to 9:00?

-Rory would certainly count as a first-aider.

-But Rory was on shift at the hospital.

James Green has short hair.

A known blackmailer, increasingly desperate, though the timing's impossibly tight.

-Mm.

'Course, it might just have been someone collecting for charity.

-That time of night?

And annoyed?

-Either way, this witness puts Oliver Cowie still alive at 8:50, and we know he died in the next hour.

Let's make a list of sportswear and leisure brands that use a plus-sign-type cross as a logo.

-Sure.

-Just checked with the hospital.

Rory Fisk went to grab a burger on his dinner break for two hours and 20 minutes.

-Rory and Lyn?

-Two bereaved parents find love after fleecing the deceased.

I mean, who would question it?

♪♪ ♪♪ [ Indistinct conversations ] ♪♪ -I'm just off shift.

I was about to go home.

-Where were you between 8:30 and 11:50 on the night of the murder?

Because we know you didn't just nip out for a burger.

-I was with a friend.

A girlfriend.

Amy Lightfoot.

She's a nurse practitioner here.

It's early days, but I didn't want anyone to know, especially my daughter.

-Why on earth didn't you tell us?

Your friend's been murdered.

-Because it had nothing to do with Oliver.

Here Amy's contact details.

[ Camera clicks ] Look, Petal's been blindsided by her mother death, she's got important exams coming up, and she's upset that her best mate is going away.

Now this nightmare?

I really didn't think it was a good time to throw another curve ball at her, and it just wasn't relevant.

-You do realize we're gonna have to check your whereabouts with Miss Lightfoot?

-Yeah, of course, but please, just don't say anything to Petal.

I don't think she can take that right now.

♪♪ ♪♪ -What better place to dispose of bloody clothes than a hospital?

Just put on a fresh pair of scrubs, and bingo.

Plus he's a cyclist.

And did you notice he was wearing a track suit?

-Max, I have four track suits.

-Scroll left for what I've dug up.

Nothing I can find that has the logo on the back, though.

-What about an old design or a club logo?

-I'll keep on it.

-Amy Lightfoot confirms Rory Fisk's alibi.

-Any evidence?

-Absolutely.

She even took a selfie of them at the flat.

Time, date, coordinates, there.

[ Notes playing ] [ Dissonant notes play ] ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ -Oh, you idiot.

♪♪ [ Buttons clicking ] ♪♪ [ Cellphone buzzing ] ♪♪ -Max.

-Eric Heidegger's dad.

He's something senior in a German shipping firm, right?

-Go on.

-But that doesn't mean he's German himself.

He said his wife was flying to Bern.

Well, that's in Switzerland.

♪♪ ♪♪ -I usually go jogging.

I went to see him that evening.

I admit it.

But I didn't even go inside the house.

I was out for a run.

I had an important shipment to coordinate that night, and I wanted to clear my head.

-You run around there regularly?

-No, but I was upset and worried about my son being suspended, so I decided to talk to Cowie about it as fathers.

To reason with him.

I know where he lives.

Eric used to be friends with his daughter.

-Mm.

Until Oliver Cowie found out Eric introduced her to cocaine and banned him from the house.

Did you know about that?

-Yes, I knew.

I knew that's what Cowie thought.

But it was Flo who bought the cocaine, not Eric.

You think I wouldn't know?

And then a few days ago, Cowie accused Eric of obscene graffiti which he didn't do.

He was going to be excluded in his final year.

-And you were angry.

-Yes!

I went for a run, and then I went to see him.

But I didn't kill him.

Why would I?

-You lost your temper.

Eric's academic career over like that, and this man wouldn't listen.

-To the contrary, he did listen.

He was really very nice about it.

Mr.

Cowie said he had reconsidered, and he would review his case first thing.

-Okay.

So you sorted it out nicely, off you jogged, and then when you found out he'd been killed, you didn't come forward because...?

-I wanted to make things better, not worse.

My son was already in trouble with cocaine.

He has one chance to get these exams.

I know I should have told you, but I didn't want the association.

I have my visa to think of.

-You must have known you were a key witness.

-I didn't have anything useful to tell you.

-Mr.

Heidegger, you were seen with the victim less than an hour before he was murdered.

We'll decide what's useful.

-Why would I kill the man who was about to clear my son's name?

-Well, we only have your word for that.

-I told you, I was working that night.

You can check.

My colleagues would have mentioned it if I came in covered in blood.

So would the schoolkid who nearly knocked me over on the corner.

So would the guy at the corner shop who I bought cigarettes from.

Check it, please.

-We will.

Believe me.

-So, either someone visited Cowie moments after Alex did -- unexpected, unplanned, and wasn't seen... -Or he's lying.

Let's check out the corner shop, schoolkids out at that time.

And let's follow up on his comings and goings at Imperial Wharf.

-We've got authority for a PACE house search.

-We don't need it.

He's invited us in.

-Confident.

-Or calculated risk.

The more he cooperates, the less guilty he appears.

-He could hardly look more guilty.

♪♪ It's been washed, but if there's blood on it, we'll find it.

-Well, he may have had several, anyway.

-He doesn't.

Mum gave it to him.

-Your father gave us permission to search.

-I know.

I called him.

I wanted to tell him I lied.

I wasn't here that night.

I left after Mum went to bed.

Can we talk somewhere else?

-Sure.

-I thought I was getting done for tagging.

I didn't say 'cause I thought you'd do me for vandalism.

-Yeah.

It's a shame people keep blinding those security cameras, else we'd check.

-I was with someone who can back me up.

Flo.

She called me, wanted to come out and help me tag.

-So she wasn't at Petal's?

-At first.

Then Petal covered for us.

We weren't supposed to see each other after the coke thing.

-So what time did Flo get to you?

-Maybe 10:00.

She'd come with me before.

It wasn't the art, really.

She just liked breaking the rules.

-What did you do after?

-Went back to Petal's.

She was asleep.

Her dad was at work.

I left later on, like 3:30, snuck back in here.

-And what did you do in between?

-What do you think?

You think my dad did this, right?

There is no way.

He's always talking to me about honor and trust.

I feel bad even sneaking out.

All I ever do is let him down.

I -- I thought maybe if I could get into art school, he'd be pleased.

-You're talented.

-Tell that to them.

Doesn't matter how talented.

I've still got to finish school to get in.

-Oh!

Then finish.

Go back.

Knuckle down.

Do your best.

Make it happen.

[ Knock on door ] -Priya.

♪♪ -The corner shop owner says he gets dozens of joggers, but he thinks he recognizes Heidegger's photo, and he recorded a cash sale for a packet of cigarettes at 21:15 just like Alex said.

Got it.

See you there.

Eric Heidegger's phone records.

-On it.

♪♪ ♪♪ -I told you it was my fault.

If I hadn't lied, if I'd stopped being so selfish and just stayed at home... -If you'd stayed at home, you could have been hurt too.

All you did was go and see Eric.

That's forgivable.

I forgive you.

So would Dad.

-Would it be all right to have a few moments alone with Flo?

-That's me off home now, Lyn.

-Thank you.

[ Door opens and closes ] -Flo, we need to know the truth about what happened that night.

And I think you want to tell someone.

-Uh... I went to Petal's.

And I was already so angry at Dad anyway.

-We know from Eric's phone records that you called him at 8:45, but you didn't get to the bridge until 10:00.

So, what time did you leave Petal's, Flo?

I can ask her, but I'd rather you told me.

-I left Petal's right after I called Eric, and he told me Dad was having him kicked him out of school.

So I went and scored some coke from the guy I got it from before.

I just wanted to punish Dad.

I wanted to hurt him.

-Okay.

So, who did you get the coke from?

Where did you go?

-Please don't make me grass.

-We'll be discreet.

We just need to know what time you were there.

-He's in the year above me.

It's just like by word of mouth.

-I'm gonna need his name and number, okay?

-Did you take him to your home, Flo?

-I don't even know him.

-Did you take anyone to your home?

Or send someone to punish your dad?

-No.

No!

I -- I just -- I went to meet Eric, and then we went back to Petal's.

I loved my dad.

'Course I did.

I just wanted to get away from all the aggravation, all the fighting.

It never used to be like that at home.

Even Carmel had a bust-up with Dad over something.

It was like a war zone.

All 'cause of Japan.

And I blamed Dad.

-I always thought I'd know if my kid was doing drugs.

-Well, we'll check out the dealer, close him down.

But she seems to be carrying a lot of guilt.

-She wanted to go to Petal's this afternoon.

I was going to say no, but maybe she needs her friend.

♪♪ -Carmel cycle to work?

-Sometimes.

If the weather's okay.

[ Door opens ] -Carmel?

♪♪ -I was at home, like I've told you, watching telly.

-What did you watch?

-That vet thing with Mr.

Charisma.

I tape them.

Isn't there some box that proves what you've seen?

-Your phone would be helpful, if you wouldn't mind.

And if you could unlock it, please.

-What did you and Oliver Cowie row about a few nights ago, Carmel?

-I-I-I don't... Nothing.

-You're here voluntarily, but we could detain you if need be.

-I wanted to go with them to Japan.

Well, they'd want a cleaner in Tokyo, wouldn't they?

But Oliver said no.

It was too complicated with visas and whatnot.

And they didn't need as much now Flo's older, he said.

I lost my temper, briefly.

But he was right, of course.

And he said he'd spread the word about another client for me, so... -And how did that make you feel?

-Honestly?

I was hurt.

I've no kids of me own, and they'd told me time and again I was part of the family.

I felt used, I suppose.

Abandoned.

Disposable.

Yes, I was very upset.

But I didn't kill Oliver, if that's what you're getting at.

Might be a lonely cow, but I'm not a murderer, thank you very much.

-I'll see this is returned to you.

♪♪ ♪♪ [ Door closes ] ♪♪ Her phone places her at home.

-Assuming she was with it.

-Hmm.

Right, let's go over what we've got.

We know Heidegger called on Cowie at 20:50.

Either he went in and killed him or he left and someone else, on a bike, came shortly afterwards.

-Carmel rides a bicycle, she has a grudge, and she is a key holder.

-But she'd have cycled all the way back to Battersea covered in blood, then turned up cool as you like at the scene the next day.

-Would she have a choice?

-Heidegger was definitely back at his Imperial Wharf office, 21:15.

Nothing unusual.

-What about the schoolkid he said he bumped into?

-That could be anyone.

Fernlea Close covers three catchment areas.

But do we need it, Max?

If we can place him in the corner shop, Alex Heidegger couldn't have done it.

-The owner said he wasn't sure.

What about the first graffiti?

Did we get anything back from the witness who saw Eric do it?

-I'll chase it now.

-Something's missing.

♪♪ ♪♪ -Shall I tell Heidegger he can go?

Max?

-Her alibi.

Oh, my God.

♪♪ [ Door opens ] -This schoolkid you say you bumped into after leaving Cowie's place -- Was it a girl or a boy?

-A girl.

She nearly came off her bicycle.

-Let him go.

-The pupil, the witness who grassed up Eric... -I know who she is.

♪♪ ♪♪ [ Door opens ] -I'm working, Flo.

-Can't you take a break?

-No.

You won't pass your exams if you don't finish your essay.

-Exams can wait.

I need you.

[ Vehicle approaching ] -What is it?

-You need to let us in, Rory.

-Can't we go out?

Just go somewhere.

For a walk?

-I need to concentrate.

-Petal!

Seriously, get changed.

-Where are the girls?

-I can't do this.

I'm sorry.

-I'm the one who needs help.

I'm the one who's having a breakdown.

-We need you to stay here.

-We're going to go out.

And you're going to get -- ♪♪ ♪♪ -I didn't mean it.

[ Door opens ] -It's okay to tell her.

-You were off out with Eric, doing drugs, ruining everything.

-So you were trying to help your friend.

Was that what it was, Petal?

-I thought if her dad understood, if he knew what I knew, he'd catch her before she fell too far.

-So you didn't go there to hurt him?

-I went to warn him, how messed up Flo was getting.

And maybe... he'd even let her stay?

But he was angry with me.

For making stuff up about Eric.

But I was only trying to protect you, Flo.

He said he was disappointed in me, that I needed to -- to back off, to go home.

Never heard him talk to me like that.

-That must have been very painful.

-He said she wasn't my responsibility and that I wasn't... ...that we weren't... family.

Like all my caring was for nothing again.

And I'm alone.

I'm nothing.

-Abandoned.

Disposable.

-He went to reach for his phone to call my dad.

I just wanted to stop him.

♪♪ -I'll call the duty social worker.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ How does a kid survive something like this, either Petal or Flo?

-A good therapist, for starters.

It's a long road to forgiveness, but we have to hope that's possible.

Uh, I just need to make a call.

[ Line ringing ] Astrid, it's me.

Look, I'm sorry about the other day.

Can we talk?

Great.

8:00.

And listen, there's a favor I need to ask you.

[ Doorbell rings ] ♪♪ -Mr.

Heidegger?

I'm Astrid.

Detective Inspector Max Arnold's friend.

-DI Arnold left a message.

Um, he said you have connections at the art college my son wants to go to.

-I can certainly offer your son some advice, maybe get through the door for an interview.

-It's very kind of you to spare the time.

Please.

♪♪ -I'm off home if that's okay.

-Yeah.

Sick of the sight of you.

-Don't stay too long, okay?

-No, I'm gone.

As soon as I've finished my paperwork.

-Right.

Good night, guys.

-Good night.

[ Door closes ] ♪♪ -She went down fine.

-You've got the magic touch.

-Oh, please.

But I'm working on it, babe.

I know you do a lot.

Too much.

And I'm sorry.

-Hey.

It's what I signed up for.

So, what's for dinner, Nigella?

-Oh, well, tonight you have the choice of pasta pesto or something I like to call pesto pasta.

-I'm feeling the pasta pesto.

[ Pasta rattling ] -Mmm!

Good choice.

Can you cook it?

-[ Laughs ] -You're early.

-You're late.

I stopped to see your budding Banksy earlier.

I like him.

-Thanks, Asti.

I know how busy you are.

-Not too busy for the posh dinner you promised me in return.

-Kebabs okay?

-Do I have a choice?

-Oh, yeah.

Lamb or falafel.

Just so you know, I've signed a license on the boat.

A year, with an option to renew.

And I've officially changed my address.

You were right.

It's time to move on.

-So we have something to toast.

♪♪ -I'll be right in.

♪♪ ♪♪ [ Chuckles ] ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪