Sam suspects that Jack Turner intends to assassinate Fatima Zahir, a Pakistani presidential candidate opposed to the sale of the dam he is trying to buy. Sam and the team race to save Zahir's life, only to discover Turner has an even more important target - a scientist possessing a deadly secret that implicates Byzantium's own client.

Byzantium is ordered to kill Jack Turner, but when the assassination attempt fails, Sam is exposed as a spy, and trapped inside the house. Turner produces the evidence he has against Byzantium's client, while Sam - secretly being poisoned to death - at last begins to recover terrible memories that explain why the Hourglass conspirators want her dead.