Quentin Tarantino’s “Inglourious Basterds” (sic) is crazy in ways you don’t expect it to be crazy, even though — this being a Tarantino picture — you probably expected it to be crazy.

Rumored as some sort of “Dirty Dozen”-style yarn about Jewish-American commandoes killing Nazis during World War II, the movie is actually a measured collection of slow-burning dialogue scenes, interrupted by bursts of violence and strung together to become a wish-fulfillment alternate history of the war.

Those commandoes are indeed part of the mix, and so is a plot (two different plots, in fact) to kill Adolf Hitler and other Nazi officials in a grand movie theater in Paris.

Of course the finale happens in a movie theater: Tarantino has again steeped his film in the movie history he loves.

And yet, if there’s a model for the way “Inglourious Basterds” rolls out, it’s opera. As opera is a series of long scenes of people planting their feet and singing arias and duets, so is this movie a string of elaborate, sometimes static, duets of dialogue. In this case, it’s punctuated by machine-gun fire.

The knockout opening sequence sets the tone: an astonishing scene of calm menace as a Nazi officer (Christophe Waltz) quietly, even charmingly, interrogates the owner of a French farmhouse.

Tarantino tops himself with a later set-piece that takes place in a basement tavern, which involves a dashing British agent who used to be a film critic (a film critic, people!) posing as an SS officer (Michael Fassbender, from “Hunger”). He’s made contact with a famous German actress (Diane Kruger) and some nervous members of the “Basterds.”

The outcome of this scene reminds us that Tarantino, for all his love of cinematic traditions, has spent a great deal of his career demolishing our expectations of how a movie plays out.

For instance, the most notable story line suggests climactic revenge for a young woman (Melanie Laurent), but it will not work out the way we suspect. And the film’s biggest star, Brad Pitt, appears in maybe half the movie.

Pitt is easily eclipsed by Waltz’s witty and sinister performance, which won him the Best Actor prize at the Cannes Film Festival.

Who is Christophe Waltz? An Austrian-born actor in his early 50s who has spent much of his career in Euro-TV, that’s who.

It’s typical of Tarantino that he would find this guy, unknown to American audiences, and casually present him in one of the best performances in recent memory.

Watching “Inglourious Basterds” is head-spinning: In close-up, everything is skillfully rendered, but if you stand back to take in the big picture, you might well wonder what on earth Tarantino is doing rewriting 20th-century history for the sake of a loony movie fantasy.

I haven’t resolved that yet (I walked out of the theater thinking, “Did what I think just happen really just happen?”), but I was riveted in watching this thing. Nobody else could’ve made it.