Mac defends traditional marriage, while the rest of the gang reap the rewards of wedded bliss.
Dennis' marriage to Maureen Ponderosa hits a snag, as does Charlie's marriage to Frank. And Dee, it seems, has come between Bill Ponderosa and his wife
Mac, Charlie and Dennis buy a boat to "throw some P. Diddy-style parties," as Mac puts it, and, Charlie insists, to harvest shrimp (or barnacles). They end up with a run-down houseboat, the Drowning Sailor, and Mac and Dennis order Dee (who didn't invest in it) to clean it up. Frank, sledgehammer in hand, offers to help.
Mac finally gets his big break after correctly answering a radio station's trivia question. Meanwhile, Frank, Dennis and Dee start their own bar-banter podcast.
There's a heat wave in Philly, so Mac and Charlie decide to fix up an abandoned pool after they're denied admittance to a swim club. Meanwhile, Dennis and Dee try to beat the heat in a more "dignified" manner.
After Mac's mother burns her house down with a cigarette, Mac decides that she should move in with Charlie's mom. Meanwhile, Frank offers to take care of the ailing Dee because he wants her to take care of him when he's old.
Dee's pregnant, and she tells the guys that one of them made her that way during a Halloween party that none of them can remember. So they try to piece the evening together, "Potemkin"-style, aided by Artemis and the McPoyle brothers.
The gang is growing as a result of a blast from the past, which also prompts Dee to reconsider her future.
Dee takes a job as a substitute teacher and decides to take her students on a field trip to Broadway. The principal won't allow that, so it's a screening of the gang's movie---"Lethal Weapon 5"---instead.
Charlie is going batty trying to keep rats out of Paddy's basement, so the gang decides to throw him a surprise party to cheer him up.
When the gang goes to Atlantic City for a charity benefit, Frank, Dee and Mac get lost en route. But Dennis and Charlie hitch a ride to town and have the time of their lives.
Dee's blessed event is fast approaching, but the father's identity remains a mystery---to the gang, at least. So they throw a party and invite all of Dee's former flings.
The gang sets out to discover the joy of Christmas. Their holiday adventure includes a sleighful of stolen toys, childhood videos, naked elves and a bloody encounter with Santa Claus.
