At the height of the First World War, two young British soldiers must cross enemy territory and deliver a message that will stop a deadly attack on hundreds of soldiers.

One night in his near-empty tower block in contemporary London, Adam has a chance encounter with a mysterious neighbor Harry, which punctures the rhythm of his everyday life.

Fifteen years after vanishing from the CIA to start a family, elite spies Matt and Emily jump back into the world of espionage when their cover is blown.