Enigma

In March 1943, during the height of World War II, Tom Jericho returns to Bletchley Park after recovering from a nervous breakdown. His breakdown was triggered by a failed love affair with Claire Romilly, a fellow crypt-analyst.

The British crypt-analysts face a critical situation as the Nazi U-boats have changed their code reference, causing a blackout of crucial intelligence. They must crack the Shark cipher quickly to track U-boat locations and save lives.

Tom learns that Claire has mysteriously disappeared just days before his return. Determined to find her, he enlists the help of her housemate, Hester Wallace, to follow the clues regarding her whereabouts.

A convoy of thirty-seven American ships is under threat from the U-boats, which gives the code-breakers less than four days to decipher the new Shark cipher. The urgency escalates as time runs out.

Searching Claire's apartment, Jericho discovers stolen German transmissions hidden under the floorboard. These transmissions could potentially help in deciphering the new Shark cipher that the Brits are struggling with.

As he works to find out what happened to Claire, Jericho is closely monitored by MI5 agent Wigram. Wigram interrogates him about his relationship with Claire, questioning whether it led to his recent breakdown.

Jericho and Hester attempt to use the enfolding Enigma machine to decode messages from the German transmissions. Despite their efforts, they struggle to get clear results, facing the complexity of the encryption.

As the German U-boats begin to attack the convoy, ships are sunk, resulting in significant loss of life. Jericho and Hester race against time to decipher the messages before more casualties occur.

Hester uncovers that the decoded messages link to a list of Polish names, revealing the grim truth about the U-boats' operations. This vital information fuels Jericho's determination to save Claire and stop the attacks.

Jericho discovers that Jozef 'Puck' Pukowski, a fellow crypt-analyst, is involved with Claire. Driven by a mix of emotions, he realizes that Jozef's motivations may be tied to a revenge plot against the Soviets.

After tracking Jozef to a Scottish village, Jericho confronts him as he prepares to meet a U-boat. The stakes rise dramatically as Jericho battles against time and danger to protect Claire and thwart Jozef's plans.

Wigram coordinates an attack on the U-boat as Jericho confronts Jozef. This tactical maneuver leads to the U-boat being sunk and Jozef's demise, averting a major threat to the British naval operations.

Though Jozef is gone, Jericho discovers that Claire is still alive but in hiding. He realizes she refused to betray her country and the tragic misunderstanding has put both their lives at risk.

The film concludes in 1946, with Jericho married to Hester and expecting their first child. As they walk through London, Jericho unexpectedly sees Claire, signaling a bittersweet reunion.