Watching Anna Kendrick in Pitch Perfect 3 is something like watching Harrison Ford in Return of the Jedi or your high school's football coach teaching health class. Here is a professional who can't find the wherewithal to hide a boredom that seems tinged with disdain. As Beca, one of the film series' singing/dancing a cappella dynamos, she again hoofs gamely through the many production numbers, but there's an aloof flatness to her delivery in dialogue scenes, like she's running lines in rehearsal for one of her Joe Swanberg indies rather than lighting up the screen in a tent-pole holiday musical sequel.
That refusal to sparkle becomes the most interesting thing in this exhausted installment, which finds the Bellas -- the collegiate a cappella troupe from the first two films -- joining a USO tour just to have something to do. When Fat Amy (Rebel Wilson) behaves abominably, Kendrick's Beca, the straight-woman foil whose reactions would usually fuel the comedy, tends to duck eye contact and mutter things like "Why are you like this?"
Give Kendrick credit: She's entirely convincing in the role of an adult annoyed to be surrounded by assholes still singing radio hits in meaningless competitions. Yes, that USO tour somehow becomes a contest, where one of the three performing groups has a shot at appearing on TV with DJ Khaled. Also, inexplicably, the tour is of the French Riviera, where everyone stays at the poshest hotels. The Bellas aren't invested in the film's competition, and the filmmakers' aren't invested in it, and you probably won't be, either.