The Bletchley Circle

Diederich...

Diederich...

Millie?

Jean will have the vapours if she catches you out here.

Jean doesn't scare me. She scares me.

Those personnel reassignments we just got - how were they encrypted?

The last batch? Ultra. Why?

Spill the beans, Susan. What's going on?

Why aren't you girls working?

Sorry, Miss McBrian, but there's a German Oberleutnant

whose orders were part of the Ultra intercept

and Susan thinks it's important.

Don't you, Susan?

Well?

I've seen him before. He's skipping about all over the place.

Maybe he's Hitler's nephew on a sightseeing tour.

Why use Ultra encryption on personnel reassignments?

Go on.

Lucy, he's Oberleutnant Dieter von Diederich.

Any other assignments?

Oberleutnant von Diederich, 7th January, reassignment.

Berlin Central to 25th infantry division, effective immediately.

Oberleutnant von Diederich, 12th March, reassignment,

Clausewitz, effective immediately.

Oberleutnant von Diederich, 24th March, battalion transfer order,

702nd Static Infantry Division, effective immediately.

Oberleutnant von Diederich, 3rd May, reassignment -

All right. Hitler's nephew doesn't get around that much.

Transferred to Clausewitz. Where is that?

Nowhere. There are no German towns called Clausewitz.

Maybe it's a person, not a place. It's also a tank division.

He was transferred from infantry to tanks and back again,

which is as daft as someone leading the show jumping

because they're good at hockey.

So who is he?

I don't think he exists.

I think he's a code within the cipher.

Code for battle orders, you mean? Perhaps.

Take it to the house.

But I don't think - You do think it's real, don't you?

You don't think it's a coincidence?

You've been ages! What happened?

We had a bet you'd been court-martialled and shot.

Well? We were right. It is a troop deployment code.

The battalion numbers indicate different geographical zones

and Diederich is the order to deploy.

So now we know where the German army's going to be in three days.

My cousin's in North Africa. This could...

Yes. It'll make a difference.

Well done all of you, I'm sure.

Now, get back to your digs, get some sleep.

Shift starts in seven hours.

Good night.

You know the map they have up at the house?Hmm.

With the markers for the armies?

All those troops are on the move now because of us.

Not bad for a few ordinary girls in a tin hut.

Why are you laughing?

"Ordinary girls". You couldn't be ordinary if you tried.

When this is over, won't we have to be ordinary?

I won't let you.

Now, shut up and go to sleep.

Mummy! We're home!

And then Mummy says, "It's time for lunch, everyone. Come inside".

Lunch at school was horrible.

Gosh, I'm sure it wasn't that bad.

It was spam fritters and tapioca.

Snotty gobbles. Eurgh!

I am going to have a lie down.

I've also got a sandwich if you'd like it.

Oh, yes, please, and I'd like a chunk of cheese.

'This is BBC Home Service News at four o'clock

and this is Alvar Lidell reading it.

Police have found the body of a fourth woman

on wasteground in North East London.

The woman, who has not yet been named,

was discovered near Warwick Green and appears to be another victim

of the killer of Jane Hart, Patricia Harris and Sophie Trent.

A spokesman for Scotland Yard

said that there were many similarities in the cases

and that they were extending their manhunt throughout the city.'

Warwick Green? That can't be right.

Mummy? Can we go and play outside?

Yes, of course you can.

Stay near the house, though.

Gap in the pattern.

Missed one.

Can we leave the table, please?

Yes, of course you can.

How was work?

Gruelling. Stephens is reorganising the department,

so everyone's on their best behaviour.

A lot of fuss and bother over nothing much.

Darling...

you know the Deputy Commissioner, don't you?

Wainwright?

I served with him in the Royal Artillery.

I don't "know" him exactly. Why?

It's a funny thing, really.

You know I'm good with puzzles and brain-teasers, that sort of thing?

I know you're the very devil with the cryptic crossword.

And you know that these poor girls they've found?

Oh, sweetheart, why on earth are you thinking

about all that horrible stuff? Oh, I don't know.

I do know, really.

The first girl Jane Hart, she was a shopgirl in Soames.

Right. You remember her? She must have served me a dozen times.

She was there and now she's gone.

I can't help thinking there but for the grace of God -

Ah...Susan. Don't be silly.

Look.

These girls...from what the papers say, they...

they weren't our type, not at all.

Out on their own at night. But I couldn't help thinking about her.

Now I think there might be something the police aren't seeing.

I think there might be a fifth girl but they haven't found her yet

because they don't know she's missing.

You know I'm good with patterns.

You really think that just by listening to the wireless,

you can tell the police where to look for a murder victim?

Oh, yes.

Timothy. Sir.

How are you? Good to see you. Nice to see you too.

This is my wife. Pleased to meet you.

Come.

Do come in.

Now, er...Timothy says you may be able to help us.

Well, I hope so.

Er...may I?

Of course.

Er...your first girl was found here, Jane Hart,

in an Anderson shelter behind a disused terrace. Yes.

Patricia Harris was found here, also Anderson shelter,

this time on waste ground.

Er...Sophie Trent here, this time in a cellar of a disused building. Yes.

Now, your fourth girl - I'm afraid we can't release her name yet.

It doesn't matter. Warwick Green.

She'd made a journey that day, hadn't she?

Well, she wasn't taken from her house, Mrs Gray, so yes.

None of them were found near their homes.

So the man you're looking for doesn't go searching these women out.

He waits for them to come to him.

That means the locations where they're found describe a pattern

that's defined by the killer, not the victims.

I'm not sure I follow.

I think we've probably taken enough of your time.

I really should be getting to work.

Yes, of course, Timothy, won't keep you.

Perhaps the Inspector has a few more minutes,

just to go over the rest of the pattern?

Darling - No, no. I'm sure I can spare another ten minutes.

Oh, well, that's... That's very good of you.

I hope it turns out to be useful.

It's er...good to see you looking so well, Timothy.

Thank you, sir.

So...a pattern, eh? Yes.

What sort of a pattern?

Imagine you're deploying merchant vessels

to take supplies outbound from Dover.

Let's say these are your ships.

Now, you hear a mayday signal from...

these...three.

That should tell you two things.

Well, it tells me I've got a U-boat under my desk.

And it tells me that this vessel... was either very lucky indeed

or it went down without a mayday call.

Yes! But no-one's going to know for sure unless they go and check. I see.

I-I think you have a gap in your list of murder victims.

Someone who, as it were,

went down without managing to make a distress call.

That would even out the time difference between victims.

Exactly.

Timothy says you worked for the Foreign Office during the war.

Yes. Clerical work.

Mrs Gray, I'm not going to ask you to breach the Official Secrets Act

right here in Scotland Yard, but, er...

it wasn't clerical work, was it?

And your husband doesn't know?

This girl you think we've missed.

How do we find her? You look at the other variable - location.

So - excuse me, sorry...

It's not a straight line like the U-boat

but let's say it's a spiral, he's circling out from somewhere.

So we track back and we look for the centre, which would be here, in Soho.

That suggests the gap you're looking for would be somewhere around here.

Why would he be leaving a pattern for us to follow?

He doesn't realise he's doing it.

People make patterns all the time but don't notice.

I'm sure you walk to work on one side of the street

and walk home on the other. Perhaps you think it's faster that way.

He's doing exactly the same thing.

He's trying to cover his tracks by moving around,

but in fact, he's making the pattern clearer and clearer,

if you know how to look for it.

Right. Thank you.

Those hedges and down through those railway tunnels.

Jamie, onto the ridge and all this stuff here.

Here you go. Thank you.

Anything? Nothing, Sarge.

Boys?