Perhaps the greatest surprise of the Hunger Games franchise to date had been the degree to which the films reversed the quality trajectory of the books. The first novel in Suzanne Collins’s trilogy was the best, with the second moderately worse and the third considerably so. The movies, however, got better and better from first to second to third. (The final book was split into two installments, as is the fashion post-Harry Potter.)

Alas, that trend has now been arrested. The Hunger Games: Mockingjay—Part 2 is the least enjoyable of the films by a considerable margin, a dull, grim, slow-moving slog. The plot, for those unfamiliar with it, involves the final assault on the repressive Capitol by Katniss Everdeen (Jennifer Lawrence) and her rebel companions. Katniss and her squad are sent by the rebel leader Alma Coin (Julianne Moore) on what’s supposed to be a relatively safe propaganda mission in areas of the Capitol already pacified by rebel troops. But Katniss’s nemesis, President Snow (Donald Sutherland) has seeded the city with deadly “pods,” containing everything from machine guns to flamethrowers to a tidal wave of oily goo—effectively turning the Capitol itself into another iteration of the “Hunger Games.” “Our gamekeepers,” he cackles, “will make them pay for every inch with blood.”

This storyline, lifted straight from the novel—the apparent idea having been that each volume of the trilogy must have its own Hunger Games of one sort or another—is decidedly ridiculous, and I’m not sure how it could have been rescued without wholesale re-writing. (Obviously, not an option.) But the director Frank Lawrence (no relation to Jennifer) and the screenwriters Peter Craig and Danny Strong do themselves few favors in this outing.

When Lawrence signed on as director before the second installment of the franchise, he (along with his leading woman) brought a moral heft to the proceedings that had been lacking in the first film. His Hunger Games films weren’t merely about a tournament in which children kill one another, they were about repression, revolution, and war on a broad scale. And while those themes are still present in Mockingjay—Part 2, they’re in scarce evidence onscreen. Instead, the movie has narrowed into a tale of a single band of (mostly) young people, lurching from one danger to another. The fact that a substantial portion of it takes place underground—Katniss’s team take to the urban tunnels of the Capitol to get away from the pods—only adds to the claustrophobia.

Moreover, this installment of the saga, the grimmest of the series by far, didn’t need the additional solemnizing that Lawrence brought to its predecessors. Quite the contrary: It could have benefited from an infusion of levity and/or velocity—two qualities conspicuously lacking. Scene after scene is held one, two, three beats too long, in an effort to advertise its Great Moral Importance. The result is a movie that is too silly to be so somber, and too somber to be much fun.

The action sequences are muddy and confused, and the lulls between them—which consist largely of tedious speechifying and long bouts of remorse and recrimination—interminable. The love triangle between Katniss, Peeta (Josh Hutcherson), and Gale (Liam Hemsworth), downplayed in the other films, is heavy-handedly restored to center stage. (Particularly painful is a scene in which Peeta and Gale compare the varying degrees of authenticity of the kisses they’ve received from Katniss.) And the final 20 minutes or so suffer from acute Return-of-the-King-itis, with narrative postscript following narrative postscript following narrative postscript.

Several principal characters from the previous films—Woody Harrelson’s Haymitch Abernathy, Elizabeth Banks’s Effie Trinket, Stanley Tucci’s Caesar Flickerman—make only token appearances in this outing. But it’s the near-absence of the late Philip Seymour Hoffman, who died during filming, that is most keenly felt. His ability to ground the series with understated irony was a crucial component of the earlier films’ success. (It borders on cruel that the last we hear from his character, Plutarch Heavensbee, is a letter delivered to Katniss that reads, “I wish I could have given you a proper goodbye.”)

Should committed fans of the franchise go see Mockingjay—Part 2? Of course they should (though perhaps with tempered expectations). Lawrence, as always, makes for a compelling Katniss, and this is, after all, the completion of a long journey. Which is ultimately, I suspect, part of the problem. This is a movie so busy being a final chapter that it frequently forgets to be a movie.