When multi-millionaire Maxwell Abbott dies, he arranges for 5 couples to participate in a winner-take-all automobile rally using his collection of classic cars. The prize: the vintage cars themselves, valued at nearly $2 million. McMillan was an old friend of Abbott's and he's pledged the collection to the police benevolent fund if he wins. It soon becomes apparent that someone is prepared to win at all costs. Forced to use Sally's old car after someone disables the classic Corvette they were supposed to use, the McMillan's set off but not before others have found their vehicles tampered with and someone phones in a bomb threat. The sabotage continues and McMillan wants to call the race off. He gets little support from the others who all have their own reasons for wanting to win the prize. When one of the participants is killed, McMillan finds himself dealing with a case of murder. The motive may not be as obvious as first appearances would suggest.

Mac and Sally find themselves investigating a murder when their host, Ewing Webley, is murdered. Webley is a very rich man having made his fortune in the insurance industry and is survived by his son Walter and his much younger wife, Rachel. Many people had a motive for killing him. His wife may have been having an affair with tennis pro Ilia Astrov who's just had his sponsorship terminated by the now dead man; as well, the man didn't see eye to eye with his son who felt diminished by his father's success. In his will, Ewing Hubley left most of his estate to his son but the investigation reveals that his corporation was on the verge of bankruptcy and that recently obtained loans were redirected to the Webley charitable foundation. A case of mistaken identity is central to the case however.

In the second episode to discuss Mac's past life as a CIA operative, he's called on by his old boss to help investigate a "sleeper," a Communist agent who has lived undetected in the United States and adopted American customs until it's his -- or her -- moment to strike. An upcoming U.S.-Soviet intelligence summit is the apparent moment. The sleeper could be anybody, even Mac's intelligence buddy, because he or she is thoroughly Americanized and could be engaged in anything, including counterintelligence. Throw in several Soviet hit men assigned to waste the sleeper before Mac uncovers his or her identity ...

The McMillans' maid Mildred is serving on the jury deliberating on the fate of San Francisco football star Luke Johnson, but one night she is attacked in her hotel. The jury is moved to a different hotel and in their vote for a decision, jurors vote to acquit Luke Johnson - except for juror Tom Ryan. Later that night when Jerry, a guard, gets a phone message for Tom Ryan from his stepmother Virginia Ryan, he and another guard go to Tom Ryan's hotel room, and find him shot to death. McMillan must now investigate two murders - the murder of Luke Johnson's teammate Mo Draper (the subject of the trial) and the murder of juror Tom Ryan. The McMillans and Charlie Enright question Luke Johnson's lawyer, the Ryan family, team manager Andrew Brille, and Jerry the guard, but several attempts are made on their lives, including an attempted shooting of Stewart at a football game, before Stewart makes a startling discovery about the way Tom Ryan died - and in turn learns the true reason why Tom Ryan was killed.

With a very pregnant Sally at home McMillan, Sgt. Enright and Mildred travel to by train to Los Angeles to attend a police convention. In fact, they're traveling on a train that was chartered for them and about another dozen area policeman by the wealthy Aaron Hildeth. He's also invited Tommy Brown, an author whose recent book revealed supposed police corruption, in the hope that he might develop a more positive impression of the police force. The cops aren't happy to have him on board and one of them even gets into a fistfight with the writer. When Brown is found shot to death in his compartment - and since there is no one other than police officers on the train - Mac correctly assumes that the murderer has to be one of them.

With Sally at home with the new baby, Mac is happy to entertain his mother, Beatrice, who has come to San Francisco for a visit. She has some big news: his sister Megan is getting married. Beatrice likes the young man but Mac's quick check of his background reveals that he has a manufactured identity and history. When he confronts him, he admits to being Randy Murphy and claims to have changed his name and history to hide his working class background from them - though not Megan - so they wouldn't think less of him. He does, however, seem to be keeping secrets and when Mac sees him in surveillance footage with a known thief, he concludes that his future brother-in-law is a con artist. With the wedding day fast approaching, Mac decides to run a little con job of his own...but then Murphy has been keeping a few secrets and has a surprise or two of his own.