Dunkirk is a $150 million experimental film in the guise of a blockbuster.

Writer/director Christopher Nolan has made a career out of crafting smarter-than-average crowd-pleasing movies that function as puzzles as well as dramatic stories.

But Dunkirk is something different when it comes to subject matter. It’s not a sci-fi, mind-bending adventure like Interstellar or Inception. It’s not a grounded take on a superhero like his Batman films. It’s not a non-linear character-driven drama like Memento or The Prestige (my personal favorite).

Nolan has historically locked down his film sets tight in an effort to prevent spoilers from leaking out. But with Dunkirk, a film based on the evacuation of nearly 400,000 British soldiers from France at the beginning of World War II, the story is already known – at least by the history books. It’s a story engrained in the British psyche.

Had the evacuation at Dunkirk failed, World War II would have gone very differently. Nolan’s film only gives hints of that greater context. It’s not much of a history lesson. You won’t learn a lot about what actually happened not because the movie is inaccurate, but because it’s focused on the psychological experience.

Nolan takes his audience through nearly 2 hours of pure terror as the men on the beach and in boats on the water live in constant fear for their lives. There’s no hope they will marshall a counterattack to drive off the Germans. Survival is the best-case scenario.

The film is rated PG-13, but is no less potent a war story because of it. The brutality exists primarily in implication, suspense, and the relentless pacing of the film accompanied by a tense soundscape from Hans Zimmer. The violence, despite being largely bloodless, feels honest. People die without fanfare. Planes are shot down without fireballs.

Dunkirk boasts some big names among its cast but it isn’t about the characters. These people do not drive the plot. They’re caught up in events larger than themselves. They are largely helpless participants only hoping to make it out alive.

Dunkirk is actively unpleasant for a lot of its runtime and I don’t think general audiences are prepared for that. The film puts viewers through the wringer almost as much as its characters.

That is not to say it’s deeply emotional. On the surface it isn’t at all. There is little dialog. Little history to the people on screen. It’s an extremely unconventional war movie, but those unconventional choices generally serve to make it a more terrifying experience. The audience does not have the luxury of the usual tropes to hang on to. We truly have no idea who will make it out alive if anyone.

Watching Dunkirk reminded me of United 93, a brilliantly simple and stripped down movie about the fateful flight on September 11, 2001. That movie makes no effort to establish characters or develop the story conventionally. It works because all of the Hollywood accessibility has been removed. We already know that the flight and all of the very mundane, average people on it are doomed. The emotion comes from forcing the audience to stare a tragedy in the face without overt commentary, canned dialog, or an emotionally manipulative score.

Dunkirk is the event and the experience. No more, no less. Your milage will vary greatly as to whether that will satisfy you.

At first I wasn’t sure that I liked Dunkirk. I don’t think you’re supposed to exactly. But after several days of reflection, I can conclude that I do like the film. It’s truly effective and I admire the drastically different approach to a war movie.

Nolan has been championing large format film since he used IMAX cameras on The Dark Knight nearly 10 years ago. Since then, select sequences of his movies have been shot using IMAX and 65mm film which is much larger than the usual 35mm stock traditionally used in features and is also of higher quality than the digital cinema formats dominating Hollywood now. Dunkirk is entirely shot using these formats and as such is well worth seeing on the largest screen and best quality projection you can find. I saw it in IMAX.

As with all of Nolan’s work, I feel it bears another viewing to truly get a handle on and I look forward to seeing it again.