Valkyrie teaches a lot about the most famous plot to assassinate Hitler, but you can't help but think that, say, a History Channel re-enactment could have done almost as well.Director Bryan Singer's movie is good-looking, straightforward and free of any trendy filmmaking gimmickry. That's a good start.Trouble is, it's skimpy on motivation and skimpy on character development. Who are these Germans trying to kill their leader, and why do we care about them - especially when we know that they failed?The result is an honorably and carefully made but oddly uninvolving yarn.Go ahead: Blame Tom Cruise. Many will. He has annoyed numerous people lately, up to and including Germans reluctant to let him shoot the film in their country. And his eyepatch and missing hand in this movie, historically accurate and all, will inspire some derision (and if it were closer to Halloween, many costumes).None of that should matter here. But the fact is, Cruise is a problem for Valkyrie, for a couple of reasons. One is that this is the rare mediocre Tom Cruise performance; he's simply not deep, magnetic or believable as Col. Claus von Stauffenberg, leader in a plot to blow Hitler up at his rural hideway headquarters.Which is tied into problem number two: We can never forget that von Stuaffenberg is Tom Cruise up there, acting. His American accent, his mannerisms, that familiar face; the movie cries out for an actor less familiar - or at least one more willing to disappear into the role.Cruise can do it; his comic turn in Tropic Thunder is the most extreme example. But here he's just solid American Tom Cruise, looking as if he'd be more familiar with a letterman's jacket than a German army coat.He's upstaged by more ambiguous, riveting co-stars, including Bill Nighy, Terence Stamp, Eddie Izzard, Kenneth Branagh and Tom Wilkinson. Nighy, in particular, as a plotter whose nerve threatens to fail him, is a compelling character, one who hints at much more behind the surface than Cruise's more bland persona.Valkyrie is a tough slog in the early going, and no one will blame you if you're confused about who's who and what's what. The actual assassination plot is handled with some skill - yes, it gets a little tense.It perks a bit more as the plot falls apart, quickly and tragically. The plotters of Valkyrie had more on their minds than just killing Hitler - they had to take over his whole evil regime with what amounted to one giant bluff.It's an intriguing gambit, but even here the film isn't quite up to the job. What's happening is so wide-ranging, so complex, that Singer can only touch on the surface of each development. It would help if we could see the failure reflected in von Stauffenberg's one good eye, but Cruise, alas, can offer little help. He's just Tom Cruise up there, with an eyepatch.2 hours. PG-13. Some violence, profanity.