The intrepid cops go undercover at a mental hospital, with Starsky as a patient and Hutch as an orderly, to investigate a number of mysterious patient deaths that have occurred at the asylum. With a female journalist, also undercover as a patient, they uncover that someone in the hospital is illegally using patients as human guinea-pigs for the testing of behaviour modification drugs...

Starsky poses as a cab driver to investigate a series of strangulation murders of cabbies, performed by a man dressed in Shakespearean costume and with superhuman strength in his artificial hand.