Kate Winslet, Saffron Burrows and Dougray Scott star in this thriller directed by Michael Apted.
In March 1943, the codebreakers at Britain's top-secret intelligence headquarters, Bletchley Park, are struggling to break a new German naval code.
Mathematician Tom Jericho is newly assigned to the unit, and thanks to his brilliant insights the apparently unbeatable code begins to reveal its secrets.
However, Tom has another, more personal, problem to solve – his former lover Claire has mysteriously disappeared, leaving only a few confused traces in her wake.
Joining forces with Claire's housemate Hester, Tom sets out to investigate.