When fans of the wry “Pitch Perfect” series first met the ragtag singing group the Barden Bellas, they were ensconced in the college a cappella bubble. “Pitch Perfect 3” finally bursts that bubble, following the Bellas into adult life. We are reintroduced to the group’s reluctant leader, Beca (Anna Kendrick), as she quits a demeaning record label job. In the same vein, Chloe (Brittany Snow) endures veterinary school, while Fat Amy (Rebel Wilson) coasts on her Fat Amy Winehouse impersonation. Discouraged by the demands of the real world, the larger-than-life Bellas reunite to join a U.S.O. tour, where they vie to perform as the opening act for the record producer DJ Khaled (appearing as himself).

With the Bellas removed from their natural collegiate habitat, the a cappella competitions that once drove the series feel out of place. Though there is novelty in casting a contemporary artist like DJ Khaled in the movie’s kingmaker role, his presence is a reminder that the demands of real-world pop are very different from the demands of this franchise’s fantasy version of a cappella. Watching the Bellas mash together pop songs without sound mixing or instruments in Khaled’s presence feels at best obligatory and at worst embarrassing.

“Pitch Perfect 3” fares best when its director, Trish Sie, treats it as a fantastical buddy comedy. A side plot reuniting Fat Amy with her degenerate father (John Lithgow) nearly takes over the movie when Amy’s father kidnaps the Bellas. What follows is the film’s funniest scene, as the suddenly spry Amy, in an attempt to save her friends, refashions sausages into nunchucks and sandwich tinfoil into explosives. In another divergence, the Bellas destroy a hotel suite, releasing a swarm of bees and lighting curtains on fire to the horror of party guests.

With a plot as unfocused as its freshly graduated characters, the shaggy “Pitch Perfect 3” gets by on karaoke logic: What makes for a good time isn’t the song you sing, but the company you keep.