When Britain declares war on Germany in 1939, Turing joins a cryptography team, led by Commander Denniston, aiming to crack ciphers created by Enigma machines, which the Nazis use to provide security for their radio messages.
Turing prefers to work alone, considering his teammates unnecessary. He designs a machine to decipher Enigma, but funding for it was refused by Denniston, so Turing writes to Winston Churchill, putting himself in charge and funding the machine. Turing places a difficult crossword in