Turn-of-the-century detective Isaac Bell matches wits with a German spy just as the world inches closer to global warfare in this novel in the #1 New York Times-bestselling series.

It's 1910 and Chief Investigator Isaac Bell, along with fellow Van Dorn detective, Archie Abbott, is escorting a Wall Street stock swindler to his trial in New York aboard the ocean liner Mauretania. Pair intend to enjoy the open sea and make use of the leisure time to plan Bell's wedding to Miss Marion Morgan, but are forced to change plans when two European scientists are nearly abducted and forced overboard. Bell springs into action just in time to stop the kidnapping, but his new charges are convinced they are still at risk. There's something in their possession, an historic invention, and there's a German munitions trust that will stop at nothing to steal it.

For war clouds are looming, and a ruthless espionage agent has spotted an opportunity to give the German Empire an edge in the coming conflict. What's worse, Bell's already a step behind. He's made the mistake of assuming it's some sort of war machine. But not all weapons are meant for the battlefield…