Mac and Stella investigate the murder of a woman who was stabbed in the heart with a wooden stake. The police arrest a woman who was kneeling over the body with blood on her, but Mac isn't convinced that she committed the crime.

A young John Doe, nicknamed 'Slick', is found lying across the rails of an underground subway. At first, he appears to have died from third-rail electrocution, but an autopsy suggests that he may have met his end by other means of electrocution. Meanwhile, Leo Whitefield is found shot dead at close range in a gallery he owns, with no sign of break in or theft, and a construction worker turns up with a fatal injury to the head.