I started to have a bad feeling about “Pitch Perfect 3” as soon as the a cappella version of the Universal Pictures fanfare faded away.

The third installment in the popular comedy franchise about an all-female vocal group begins with an explosion aboard a yacht, as characters played by Anna Kendrick and Rebel Wilson are shown running for their lives while flames threaten — as if the duo were stuck in an off-brand 1980s cable action flick. Little good can come from a musical comedy that stoops to raiding a different genre for its humor.

Then the words “Three Weeks Before” appear.

Heed this warning, because that is how long this dirge of a money-grab sequel seems to last. What was delightfully fresh and frisky in the first “Pitch Perfect” as the Bellas — a ragtag college crew of female a cappella singers — found their groove together is now an off-key dismantling of what made the concept work in the first place.

There is not much fun to be had in learning where the group’s members have landed after graduation, since they are all struggling in the real world. This is probably the only realistic detail to be found in the script.

But at a reunion, Anna Camp’s overachieving control freak suggests that her military dad can get her fellow singers a spot on a USO tour. As quick as you can say “Shooting in Atlanta is cheaper than Europe,” off our gals go to recapture their youth. Of course, there is a sort-of competition involved. But, oh, the horror, when the Bellas learn that the three other groups competing use actual instruments.

This story line soon fades away, and what we are left with are rather canned renditions of such songs as DNCE’s “Cake by the Ocean,” Sia’s “Cheap Thrills” and Britney Spears’ “Toxic.” Elizabeth Banks and John Michael Higgins return as an excuse for Higgins to continue to make mock-sexist remarks about mom jeans, and to introduce the group like this: “As these women approach 30, and cease to be of value as human beings ...”

Kendrick basically sleepwalks through this third go-round. That leaves Wilson’s character, the loud-and-proud Fat Amy, to do most of the heavy lifting.

The lone musical number that lifted my spirits comes late in the film, when Kendrick’s Beca brings up her fellow Bellas to join her in a glossy rendition of George Michael’s “Freedom! ‘90.” But as soon as it was over, I was only too happy to make a break for the lobby.