A fascinating story is tepidly told in George Clooney’s history-based tale of a group of art experts who joined the US army during the waning days of World War II. The mission of these specialists, called the monuments men, was to minimize the destruction of surviving cultural masterpieces and to track down pieces stolen by the Nazis and return them to their rightful owners.

This material was covered quite well in the 2007 documentary “The Rape of Europa,” which Richard Berge, Bonni Cohen and Nicole Newnham adapted from Lynn Nicholas’ 1995 book. Clooney and Grant Heslov have based their screenplay on Robert M. Edsel and Bret Witter’s 2010 tome, but it’s a loose adaptation that doesn’t hesitate to fiddle with the facts in order to meet the expectation of a mainstream audience. That’s evident in the alteration of the names of the not-so-dirty half-dozen-plus one that, in this telling, form a close-knit band of like-minded brothers.

Clooney himself plays Frank Stokes, a Harvard museum curator who begins the film by persuading President Roosevelt, after the bombing of Subiaco in 1944, to authorize the group. He then enlists its other members: art restorer James Granger (Matt Damon), architect Richard Campbell (Bill Murray), sculptor Walter Garfield (John Goodman), theatrical producer Preston Savitz (Bob Balaban), alcoholic museum administrator Donald Jeffries (Hugh Bonneville) and painting teacher Jean Claude Clermont (Jean Dujardin). After undergoing basic training in England, they follow the D-Day invasion onto the Normandy beaches, splitting up to undertake specific tasks. Campbell and Savitz form one pair and Garfield and Clermont another, while Granger sets off alone for Paris to confer with Claire Simone (Cate Blanchett), a former assistant museum curator who’s hesitant to cooperate because she fears the allies will appropriate whatever French artworks they find for themselves, and Jeffries repairs to Bruges to protect a Michelangelo Madonna and Child from the retreating German forces. Meanwhile Stokes co-opts young private Sam Epstein (Dimitri Leonidas) to serve as his driver and general factotum.

This précis points to one major problem with the film: it divides things up into individual threads involving one or two members of the unit, shuttling among them in a way that creates a lumpy, episodic feel. Nor does the script manage to present the overall theme in a crisp, decisive fashion. There are periodic high-sounding speeches about how the preservation of the artifacts embodies the cultural salvation the war is being fought to insure, but frankly they’re neither written nor delivered well enough to be emotionally satisfying. And the attempt to give the mission a central catalyst by emphasizing the recovery of two important works—that Bruges Madonna and the Ghent Van Eyck altarpiece—as its capstone has the effect of reducing the other paintings and sculptures being looted for Hitler’s planned Fuhrer Museum in Linz to a supporting status they hardly deserve. The horrors of the Holocaust, too, are given only occasional attention, mostly through the recollections of Epstein about his childhood in Vienna and finds of Jewish property among the trove discovered in warehouses and mines.

Meanwhile the film adds touches that have Hollywood written all over them: courageous death scenes for a couple of the crew, comic bickering among Balaban, Goodman and Murray (some of it fairly amusing, and in one instance rather touching, but all creating an uncertain tone), a twinge of romantic longing between Granger and Simone. Toward the close there’s even a failed effort at last-minute suspense with the introduction of a Russian “tribute” brigade that might beat our boys to the ultimate treasure and carry it off to Leningrad. As portrayed here, with the Soviet commander played as a scowling brute by Zahary Baharov, the episode has an almost juvenile sensibility at odds with the film’s more serious quality, and closes with a cheaply triumphal visual.

Matters aren’t helped by Clooney’s latitudinarian direction, which leaves many of the individual sequences fairly flaccid (though editor Stephan Mirrione must bear some of the blame), as well as his laid-back performance, matched by an equally subdued one from Damon and a turn by Blanchett that’s at the furthest possible remove from her extrovert one in “Blue Jasmine.” Murray and Balaban, on the other hand, share a few amusing odd couple moments, though Goodman is almost entirely wasted and Bonneville and Dujardin are given highly charged scenes that in the end fail to register the desired emotional impact. Lesser roles are often weakly taken (as with Udo Kroschwald’s ungainly turn as Goering).

On the other hand, the film looks good, with Phedon Papamichael contributing widescreen images that are predictably well-composed and, to use a term especially appropriate in this context, artful—though whether one considers the result classical or merely conventional will be a matter of taste. And Alexandre Desplat, who can usually be depended upon to contribute music that puts an unexpected spin on whatever genre he’s composing for, here goes in the most obvious direction with something that might have come out of John Williams’ bottom drawer. Perhaps he was too concerned with his cameo as a French resistance fighter to devote much energy to the score.

But the lack of inventiveness in the music merely mirrors the rest of this bland film, a prosaic, pedestrian take on a subject that should have elicited real passion from its makers. “The Monuments Men” is a routine piece of Hollywood work but nothing more. Fortunately, “The Rape of Europa” is still available to provide a more truthful and vivid alternative.