Glen "Fitz" Fitzgerald is a young marijuana dealer and former rock band drummer living in Los Angeles. When his best friends drop out of the band, the group dissolves and Fitz falls back on selling weed from his garage. He dates Monica, Abby Elliott, who works at a news company, and he lounges with his rebellious teen neighbor Jimmy, who skips school. Fitz also clings to the playful "triangle theory," a running joke that everything in the world connects in groups of three. One day, after Fitz is nearly arrested in a weed bust of one of his clients, he flees to Oakland to avoid capture. Jimmy convinces him to join a trip to visit his mother there, as Jimmy’s father James Malone Sr [Rob Riggle] plans to send him to military school for missing and failing classes.
Mistaken for a kidnapper, James gets help from a police academy graduate and ally, Officer Fogerty [Joe Lo Truglio], and they set out to find Fitz and Jimmy through their own investigation. Along the way, Jimmy tries to keep Fitz sober, preventing Fitz from smoking, while they plot and successfully switch cars to throw the cops off their trail by trading vehicles with Fitz’s ex-band mates Sheila [Lizzy Caplan] and Richie [Matt Jones], who have since become a Bakersfield tribute band.
Monica has become pregnant with Fitz’s child, but she engages in a brief affair with her married boss, Barry [Ed Helms], a revelation that complicates Fitz’s feelings. Upset, Fitz leaves Monica behind, and she pursues his trail. In the other pursuit, James and Officer Fogerty close in on Fitz and Jimmy, who spend a night in their van after visiting a diner. They are nearly captured, but Jimmy deflates their car tire and escapes with Fitz. The two have a fallout and stop at a roadside clinic, where a peculiar doctor suspects Fitz has kidnapped and molested Jimmy due to his good looks. Once Jimmy has a cast and sling, he leaves with Fitz, taking a taxi to a bar named Berlin in Oakland.
At the bar, Fitz finds his estranged father, Arnie [Rich Fulcher], who is the club owner and a drag queen performer for the bar, but Fitz feels ambivalent about him. Monica reappears and reveals she is pregnant, but Fitz doubts fathering the child after what happened with her affair. Jimmy also reveals that his mom is dead, adding another layer to the family tension. When James arrives with Officer Fogerty, a confrontation ensues in which James lashes out at Fitz, misreading the situation as kidnapping and abuse. Jimmy speaks up, sharing his own grievances about his father’s absence, and the two sides begin to reconnect. In the end, Fitz comes to realize that having a father—even an imperfect one—is better than not having one at all.
The next day, Monica turns down a promotion from her boss, who ridicules Fitz for trying to repair things with her, and she reconnects with Fitz as they prepare to care for their newborn. The film closes with a tough, hopeful note as Fitz navigates a future that blends his carefree past with a growing sense of responsibility for his growing family.
