While en route from Syria to Paris, in the middle of a freezing winter's night, the Orient Express is stopped dead in its tracks by a snowdrift. Passengers awake to find the train still stranded and to discover that a wealthy American has been brutally stabbed to death in his private compartment. Incredibly, that compartment is locked from the inside. With no escape into the wintery landscape the killer must still be on board. Fortunately, the brilliant...

Uniting with Jason, Piper, and Leo after their dangerous quest, Percy, Hazel, and Frank wonder who will be chosen to fulfill the Prophecy of Seven, completing their group's number, and sail with them to an ancient land to find the mysterious Doors of Death.

When globe trotting troublemaker Delilah Dirk and her friend Selim are accused of espionage against the British crown, they must clear their names, even if it means returning to respectability.