Robert T. Ironside, chief of detectives with the San Francisco Police Department, is shot down by a sniper's bullet while vacationing at a remote cabin. Ironside survived the attack, but became crippled from the waist down, and was confined the wheelchair. Realizing his skills as a crime-buster were too good to waste, Ironside became the head of his own special police unit; he moved into a specially-built office at SFPD headquarters, complete with sleeping quarters and exercise equipment, and inherited a crack staff: bland Sgt. Ed Brown, beautiful young Policewoman Eve Whitfield, and black ex-con Mark Sanger, who pushed Ironside's wheelchair and drove his special van. Whitfield eventually left the department, and was replaced by Policewoman Fran Belding, while Sanger graduated from law school, passed the bar, and married Diana.

As the show progressed, Mark went from being Ironside's bodyguard, to a full fledged police officer and eventually became an attorney in the final season.