Wigram: Were you surprised when you heard that Admiral Donitz had changed the weather code?

Tom Jericho: Well, the Germans were always nervous about Enigma. That was the reason Shark came on in the first place...

Wigram: But the Germans believe Enigma's supposed to be infallible, because it would take people a thousand years to figure out the settings for one day, and they are changed every day. But we don't use people for that, do we, Mr. Jericho?

Tom Jericho: No.

Wigram: No. And that is the secret inside the secret: your thinking machines. Day and night, clackety-clack, programmed with a menu provided by your amazing brain, narrowing down the infinite possibilities to just a few million. And if anyone tells the Germans about that... there goes the war.

Hester Wallace: I seem to move in an endless circle, Mr. Jericho, from one patronizing male to another, always telling me what I am and am not allowed to know. Well, that ends here.

Hester Wallace: Well done, Mr. Jericho, well done!

Tom Jericho: Given the circumstances, Miss Wallace, I think we might risk first names.

Hester Wallace: Hester.

Tom Jericho: Tom.

Claire Romilly: Poor you. I really got under your skin, didn't I?

Jozef 'Puck' Pukowski: Tell me, are we hoping for the U-Boats to find our convoy?

Pinker: Of course not.

Baxter: I am.

[receives stares]

Pinker: You c-c-can't mean that!

Baxter: What? Sacrifice a convoy to get back into Shark? Of course I would. How many men has Stalin had to sacrifice so far? A million? Two million? It's called "the greater good."

Cave: Spoken like someone who isn't in the middle of the North Atlantic at this moment.

Tom Jericho: Contact signal... Mary Jane Hawkins!

Jozef 'Puck' Pukowski: [scoffs] The Oracle speaks.

Tom Jericho: Do you have any idea what you're talking about?

Skynner: Tom's been on sick leave for the last month, so I don't think he's fully...

Tom Jericho: Enigma is a very sophisticated enciphering machine, and Shark is its ultimate refinement. So... we're not talking about the Times crossword here.

Tom Jericho: Every day, our Typex machines have to be set the same way the Germans set their Enigmas. And figuring out the settings is the hard part. That's where the code breakers come in.

Hester Wallace: What would Claire need to decipher the settings?

Tom Jericho: She'd need a crib. Let's say this tombstone was in code. If I knew more or less who's buried here, I'd have a pretty good idea what the code meant. You try to work out the settings and then type the coded message into the Enigma machine. If the message comes out nonsense, the settings are wrong. If it comes out "Mary Jane Hawkins," you've broken Enigma for that day.

Tom Jericho: I like numbers, because with numbers, truth and beauty are the same thing.

Tom Jericho: It's true though, isn't it? The Katyn Massacre?

Wigram: Oh, do shut up. There's a war to win, and Stalin's helping us win it.