Enigma

“Unlock the secret.”

At Bletchley Park in the middle of the Second World War, the German navy changes its Enigma settings, and the convoys crossing the Atlantic go dark. Tom Jericho (Dougray Scott), the codebreaker brought back to fix it, starts looking for Claire Romilly (Saffron Burrows), a colleague who has vanished. Michael Apted lets Hester Wallace (Kate Winslet) become Tom's only help, and the two of them are never sure the other is telling the truth.