When the Fitzpatrick family learns their newest member has gone missing, no one really cares... until they find out Josh stashed the profits from the baby brothel in his diaper. Fitz and Larry follow Baby Fitz' trail to Chester Vince, who happens to be holding Ali Devon hostage in the back of his van. Fitz and Larry soon join Ali, and the three of them must find a way to work together in order to keep a mentally unbalanced Chester from burning them alive in a quest to communicate with his alien overlord, before the track down the child.
When Ken refuses to accept the return of the money Pat Childs found in Baby Fitz' diaper, Larry becomes convinced that loneliness is at the root of his very strange behavior. Fitz thinks Larry's smoking the dope, but when he sees Pat Childs encroaching on their business; he heeds Larry's advice to spend more time with his father, and enlists his help to take down Pat Childs using a classic pedophila scam "The Polanski." Unfortunately for Fitz, in spending some quality father-son time, he discovers a truth about his family that would have been best kept buried.
It's a rainy night at the Fitzpatrick house, and Larry takes the opportunity to use large amounts of alcohol to con the family into playing his favorite game: 'Truth: the board game'. Truth is true to its name, and even Larry ends up discovering far more about the Fitzpatricks than he ever wanted to know. When they wake up the next morning to find a freshly dug grave in the backyard and a missing Elaine, the family must band together in order to re-discover those truths and figure out what happened the night before.
Wedding bells are ringing at casa Fitzpatrick as Ken and Elaine get set to re-tie the knot, and everyone is getting into the act. Everyone except for Fitz, who is convinced the wedding is a secret ploy to bring down Fitzpatrick motors once and for all. In order to stop the impending nuptials, Fitz teams up with unlikely ally and bedfellow, Paula Childs to help expose her father's nefarious plans. More than kissing cousins are revealed when Pat Childs shows up at the ceremony with a truth bomb that will sever ties with Ken and Fitz once and for all.
Still reeling from the shocking truth about his father, Fitz takes a drive down memory lane that leaves him with an even bigger identity crisis than he started with. Now that Fitzpatrick Motors is defunct, Fitz gets Josh and Larry to help him steal back "his childhood car, Betsy", in hopes of selling her off to the highest bidder. Along the way he gets swept up in a flood of nostalgia that blurrs the line between man and machine. Meanwhile Ken, who's out to relive some old memories of his own, gets a rude spiritual awakening when he tracks down a lost love from his ...
After accepting Pat Childs' offer to work at The O-Mobile dealership, Fitz quickly learns that life in the corporate world is not the cakewalk he hoped it would be. Thanks to Larry, Fitz discovers he could be in for a big pay out if he figures out a way to get canned. Yet, despite best efforts Pat refuses to give up on him leaving Fitz saddled with a major presentation to give that leaves him one step closer to embracing his inner Childs.
Twas the night before the night before Fitzmas but the only visions dancing in Fitz' head are of his face plastered on O-mo billboards around town. As part of his new O-mo image, Fitz has decided to give up drinking which prompts a visit by three ghosts to show him the impact his newfound sobriety will have on the people around him. With the whole Fitzpatrick clan scattered, Larry must scramble to rally the troops if he hopes to save Fitz from going down the wrong path.
When Larry finds evidence of a lost family fortune, it gives him the leverage he needs to persuade the rest of the Fitzpatrick clan to save Fitz from the clutches of Pat Childs' evil O-Mo empire. Now all they have to do is find where the money is hidden. Meanwhile, thanks to the ghost of Christmas future, Fitz has been driven to drink again. Once reunited, the Fitzpatricks must expose Pat Childs for the fraud he is if they hope to learn the true meaning of Fitzmas -- cold hard cash.