It is January 1855, and the Crimean War rages on. With the dreaded Crimean winter upon them, the allied troops may have to endure the bitter cold under canvas, waiting for a springtime siege of Sebastopol. Desperate to put an end to this stand-off, the British devise a dangerous plan, in which Phillip Hazard, the new commander of the steam-powered Huntress, must act as a spy. Under sealed orders, Hazard sails to Odessa, along with his brother Graham and his rough-and-ready crew from the Trojan. After smuggling himself ashore, Hazard is forced to rely on his duplicitous first lieutenant as his only means of escape from the enemy.