Dave has a one-night stand that turns into the beginning of a relationship, which he's not ready for yet. Meanwhile, Alex seeks a new roommate now that Dave's gone, and Jane wants a say in the selection process.
Brad is strangely resistant to Jane's suggestion that they befriend a worldly couple. Meanwhile, things start disappearing from Dave and Max's apartment, and Alex holds the surprising answer to the mystery. And Alex takes an interest in an artist she meets at Dave and Max's place.
Despite the gang's efforts to get Max to reveal his sexual persuasion to his visiting parents, he once again recruits a lady friend to pose as his girlfriend. Meanwhile, Penny may have met the perfect guy, but a furor is raised when her friends discover his ignominious last name.
Brad's buttoned-down dad comes to town for some serious medical tests, and when he gets a clean bill of health, the normally subdued dude turns into a party animal, which throws his son for a loop. Meanwhile, Penny's new crush is a handsome Italian who doesn't speak English, and Penny can only speak his native tongue when she is intoxicated.
Max doesn't show much appreciation for matchmaker Brad's efforts to fix him up with a guy from the office. Elsewhere, Penny has second thoughts about bringing the very competitive Jane to her martial-arts class. And the gang suspect Dave is pining for Alex after he spends a lot of time at their old place doing odd jobs for her, but the real reason is that he misses his former digs and isn't comfortable living in Max's messy apartment.
The gang have zombies on the brain after watching a horror movie. Dave fears he's become a zombie at work and quits to pursue his dream of opening a restaurant. Meanwhile, Max and Jane compete to see who would survive if zombies ruled the world. And Penny finds it difficult to keep up with her hipster beau's friends.
The his-and-her tattoos Alex and Dave got when they were a couple are proving to be a hindrance now that they've split. Meanwhile, Max appears to be passing up a relationship with a perfect guy, so meddlesome Jane takes action; Brad serves notice that he's not going to put up with what may be the world's worst waiter, but things don't work out as expected.
Dave is overjoyed over a visit from an influential high-school teacher, but when Penny agrees to a date with the out-of-towner she discovers he's not quite the wonderful guy the gang think he is. Elsewhere, a large coffee chain sets up shop near Alex's little enterprise, so Max organizes a protest, not knowing that the new joint is owned by the guy he's been dating.
Penny wants out of Alex's never-ending girls' nights out, especially after a cooking class with a rude chef. Meanwhile, Dave moves into Max's place, and in a moment of drunken inspiration, the two decide to track down the guy who spirited Alex away from the wedding ceremony. And Jane convinces Brad that they need a night out alone.
Alex and Dave hope to prove they can get along by dragging the gang to a concert by a band they enjoyed in college. But the mood sours when Dave runs into members of his old fraternity, who delight in telling them they viewed the notorious wedding video. Meanwhile, Penny, who once had a fling with a guy in the band, is on a mission to get backstage.
In the season finale, a surprise invitation to the nuptials of an old slacker buddy leads to Brad and Jane uncovering something disturbing about their marital status. Meanwhile, a depressed Penny asks Derrick to be her date and pretend they're engaged. And as the ceremony draws closer, the bride-to-be worries that Alex is a "wedding jinx."
Sibling rivalry rears its head when Jane and Alex have a difference of opinion regarding Jane's literacy group. Meanwhile, Dave scores a date with the comely coach of a women's lacrosse team but finds she has a peculiar quirk; Penny gets a long-overdue assistant and tries to be a "cool boss," with lukewarm results.