MacMillan's investigation of a suspicious burglary finds him crossing paths (and swords) with a number of his and Sally's friends. Mac, Sally and Sgt. Enright go undercover to a costume ball, where Mac is confident the culprit will strike.
The McMillans befriend Billy Benton, quarterback for the Hawks, who is either innocent or involved in a plot to throw the game. A $75,000 bet was made against the Hawks, and the bettor intends to collect at any cost, even murder.
Mac's ex-pug pal Freddie O'Neale becomes a target for murder after he claims he can identify The Dutchman, a notorious jewel thief whose face is unknown to the police and to the posh San Francisco social set whose treasures he plunders.
The famed "bag over the house" episode (Rock Hudson later explained that the production company had way overspent the preceding episodes and had to do this one on a shoestring, with no additional sets and only six guest actors) features Mac investigating a psychotic killer who targets socially prominent people. The killer goes after Mac and Sally by drugging their drinks and calling up a pest-exterminating company, which encloses the entire McMillan house in a gargantuan, airproof and soundproof bag and starts pumping poison gas inside. Mac and Sally awaken and can't ...
Numerous bits of evidence indicate McMillan's former girlfriend shot and killed her husband, but the commissioner wants all of the facts before an arrest is made. (Script recycled and expanded from "Ironside", Season 2, Episode 9, An Obvious Case of Guilt, which aired 11/14/1968).