At Bletchley Park, a brilliant mathematician races against time to crack the latest cipher used by Germany to send encoded messages through its Enigma machine. During the assignment, he falls for a female colleague, but later fears he may have been confiding in a traitor to the Allied cause. Second World War romantic thriller, based on the bestseller by Robert Harris, with Dougray Scott, Saffron Burrows and Kate Winslet.

The story of the WWII project to crack the code behind the Enigma machine, used by the Germans to encrypt messages sent to their submarines.