During the 1916–17 season, the Emersons return to Egypt through submarine-threatened waters and immediately find a fresh corpse in a looted tomb. A warning orders them to abandon the investigation, while Nefret reveals evidence suggesting that Sethos may be assisting Germany rather than Britain.
The family divides its efforts between the murder inquiry and wartime intelligence work connected with the British advance toward Jerusalem. Ramses undertakes the most dangerous part of the mission, leaving Amelia and Emerson to determine whether Sethos is a traitor, a double agent or the target of another deception before the information he holds changes the campaign.