This detective drama series was based around two mis-matched detectives. Lieutenant James Dempsey was seconded to SI-10, a new undercover section of Scotland Yard, for his own protection following a corruption scandal in the New York Police Department. Once in London, Dempsey was partnered with a beautiful female Detective Sergeant named Harriet Makepeace, who preferred to be known as "Harry". Together, they worked under the extremely watchful eye of Chief Superintendent Gordon Spikings. Dempsey and Makepeace never really agreed with each other's methods of police work, but they always managed to get the bad guys.