PJ, Stephanie and Stephanie’s new boyfriend, Lance, are on their way to Italy when PJ is called to the first class cabin, where her mystery date awaits. Meanwhile, the trip turns out to be a bit of a disaster for Stephanie. Back home, the guys are concerned that Bobby isn’t answering any of their calls or text messages, leading them to worry he might have been kidnapped. Brandon is concerned about impending format changes at the radio station. Andy seems to have sold his soul to the devil in his new job as a big-time corporate lawyer. And Mike makes the big mistake of sleeping with a waitress from Crowley’s and then not calling her afterwards, prompting the entire gang to be banned from the premises for two weeks.
Stephanie has just completed her book, and three publishing houses are hungry for it. Her sudden success in writing a book about relationships leads her to suggest that one way for PJ to find Mr. Right is to host a singles dinner party. Unfortunately, the night turns out to be a disaster for just about everyone except Kenny, who suddenly seems to have found his mojo. Meanwhile, Andy has hired a very attractive nanny, but her healthy lifestyle is driving him crazy.
After Mike arrogantly proclaims he can make a shirt from scratch, he, Kenny, Brendan and Bobby decide to hold a shirt contest. Each one will have $20 to spend on materials, and the one to make the best shirt will get free booze for a month. Meanwhile, PJ decides to write a book with a popular Eagles football player, drawing the ire of her Chicago Bears-supporting friends. Andy has been spending long hours at the office with his new coworker, just as Bobby begins spending more time at Andy’s with his new girlfriend (also Andy’s nanny), Elsa. Brendan decides to become a bartender after losing his DJ job to a computer, but his first job interview delivers the shock of his life.
Andy joins a comedy improvisation class on the advice of his new coworker, who makes a shocking appearance. Brendan is sick and depressed, so he decides to engage in a little self-diagnosis and medication. Bobby is down because his girlfriend, Elsa, is having problems with her visa and might have to leave the country. Bobby has a plan, but the gang has concerns and elects PJ to talk to him. Stephanie’s book is out, and it seems her biography on the back cover is highly embellished. Nia Vardalos (My Big Fat Greek Wedding) guest-stars.
Now that it has been revealed that the coworker with whom Andy has been spending so much time is actually a woman (guest star Nia Vardalos), everyone is worried they’re having an affair. To prove they’re not, Andy sets up Mike on a date with her. PJ agrees to help Bobby plan his wedding, because his parents have turned it into a nightmare. Kenny is being pursued by Caitlin, the girl from Mike’s improv class, indicating he’s gained the mojo that Mike seems to have lost. Brendan gets a temp job in the mailroom at Andy’s law firm, but all it does is make him feel like a failure. In reading Stephanie’s new book, the guys are shocked to find thinly veiled versions of themselves in it.
It’s time for Bobby’s bachelor party, and Brendan is bummed because Bobby’s best friend is expecting everyone to pay for everything. PJ winds up going with Stephanie to Elsa’s shower, where Stephanie and her new book become the center of attention. Kenny volunteers to help with the bachelor party, but everything he does is exactly the opposite of what Bobby wants. PJ confronts Andy over his relationship with Jo (guest star Nia Vardalos) and also spills her feelings for Bobby. That doesn’t stop Bobby’s brother, Jack, from making a move on PJ.
PJ struggles with whether to accept the advances from Bobby’s brother, Jack, whom Bobby characterizes as a womanizer. Bobby panics when not everyone has sent in their RSVPs for the wedding so he can finish up the seating arrangements. Andy and Meredith decide to try couples counseling after a big fight over Andy’s not spending much time at home. Kenny and Mike seem to have switched personalities, just as Mexican Freddy (David Pressman) makes a surprise visit to Kenny’s store to talk to him about his ticket business. Brendan is upset because John hasn’t called him back about starting a new nightclub together.
The gang arrives at the home of Bobby’s father, a luxurious ranch. PJ immediately gets swept up by Bobby’s brother, Jack, but tensions between Jack and Bobby threaten the entire weekend. Mike connects with a beautiful older woman (Mimi Rogers). Kenny gets fashion advice from Stephanie. Brendan is disappointed when he finds out John, the guy with whom he wants to open a new bar, doesn’t show. Bobby spends the entire time trying to keep his lecherous father from flirting with every woman in the place. And Andy offers to save the day when an important member of the wedding party gets kidney stones.
It’s the day of the wedding rehearsal and, with Jack missing in action, Bobby decides to make Mike, Kenny, Brendan and PJ his “best men,” while PJ is determined to set things right between Jack and Bobby. Kenny and Stephanie try to keep a secret from the rest of the gang. Mike finds out that Maggie (Mimi Rogers), the woman he stayed with the night before, just got divorced. And the entire gang confronts the reality that, with Bobby’s marriage, they will be entering a new phase in their relationship with one another.