Jim is wounded and left for dead in the city's sewer system while chasing a burglary suspect, and Sam puts pressure on the crook, Layton, to try and find his injured partner.

The squad entertains a visitor from Scotland Yard, Inspector Murchison, who's trailing jewel thief Dandy Phelps. What they don't know is that the real Murchison was murdered upon arriving at the airport, and that their guest is really Harry Wade, Phelps' double-crossed partner, who's out to gain sole control of the stolen jewels.