James Dempsey was a tough New York cop who got himself into a lot of trouble by killing his partner during a corruption investigation. With things too hot for him in New York, Dempsey was seconded to London's elite SI10, where he was assigned to work with Detective Sergeant Harriet Makepeace, under the supervision of Chief Superintendent Spikings. Dempsey found British police methods slow and infuriating, and his new colleagues considered him a violent maverick, entirely too attached to his .357 Magnum. The immediate antagonism between was countered by a strong physical attraction, and while they fought continuously, they made a good, effective team.