A vicious war between two nations is coming to a head, and the final movements are centred on the sailing ship Cassandra. Along with a very strange cargo, Cassandra carries Captain Colley, a man with his own sad burden, and the paranoid General Brennan, a woman convinced that her actions will end the war once and for all. Their grim mission goes entirely to plan, until the Cassandra gains an extra passenger - a shipwrecked archaeology professor by the name of Bernice Summerfield.

Sensing something is very wrong aboard the ship, Bernice's snooping brings her close to a terrible truth. Soon, Bernice doesn't know who to trust, and she can no longer be sure if anyone is who they claim to be...