During the early days of World War II, the Nazis change the Enigma Code that commandeers their fleet of U-boats—and now it's up to brilliant code breaker Tom Jericho (Dougray Scott) to crack the new encryption. As if that alone weren't trouble enough, he suspects a German agent may have infiltrated the British code-breaking team. Kate Winslet co-stars, along with Saffron Burrows as Jericho's fiancée, who mysteriously goes missing.