A birthday celebration for a friend of Mac's mother ends in a murder attempt.

Mac's closest friend from France, a high-ranking police inspector who recently married a San Francisco socialite, comes to town to show her off and talk business with his wealthy father-in-law. Mac can't give his buddy the royal treatment because he's just arrested a bullying lawyer for witness intimidation. The lawyer, from the inside, apparently hires a gunman to follow Mac around and fire warning shots at him. When Mac and Sally attend a fancy-dress ball, the inspector's wife (herself an old friend of Mac's) asks to talk to Mac on an outside balcony. A rifle shot rings out and she falls dead. Everyone thinks that the hired gunman fired at Mac and made a tragic miss, and the police inspector threatens to go ballistic in his search for the killer. But was Mac the real target? The plot thickens when the inspector narrowly escapes a bombing and another person -- with no ties to the gunman -- is murdered. Were the inspector, his wife or possibly both of them the targets, and why?

Mac and Sally waffle about whether or not to sell their house, especially after a break-in, Mac's surprise birthday party, an earthquake, a skeleton, spies and con men, and stolen jewels.

During a period of fiscal austerity for the city, Enright takes a lucrative position in a private detective agency in which a person blackmailing politicians might operate.

After being shot while on a stakeout, Mac witnesses a murder in the hospital while partially under sedation while awaiting surgery. Everyone thinks Mac's story is a hallucination, but he's convinced one of the doctors murdered a patient.

In an episode which introduces Mildred's sister Agatha to the cast (Nancy Walker had already committed to her own series for the following season, and Agatha was to become the new housekeeper), the McMillans, Mildred and Agatha go to visit a woman relative of Mildred and Agatha, a very wealthy woman who's dying -- but not quickly enough to suit one of her nephews, who's in debt to a loansharking company later described as "just this side of Murder, Incorporated." Threatened with death if he doesn't come up with the money right away, the nephew smothers the old lady in her bed. But when the will is read, the nephew isn't the prime beneficiary -- a young great-niece is. Someone soon guns down the niece, and the nephew (who's next in line for the money) is the prime suspect. But when Agatha sneaks onto the nephew's pleasure boat to investigate him, someone plants a firebomb onto the boat. The nephew agrees to save Agatha and gives her a life jacket, but can't get off himself before the engine explodes. Next, the McMillans discover that the murdered "great-niece" was an impersonator -- so Sally poses as the great-niece herself and shows up on the doorstep of the old lady's countrified financial manager, hoping he has some clues.

Mac goes onto temporary duty as a Navy JAG and is immediately given a case defending a Navy officer accused of murder. Mac soon discovers the victim isn't who he was supposed to be and his client isn't telling the whole truth.