Since Christopher Nolan is so fond of making us uncertain about the passage of time, let’s begin our conversation about Tenet 20 years ago—with the release of his breakthrough feature, Memento. There he told the story of Leonard Shelby, a man whose traumatic head injury left him without a long-term memory. Nolan’s narrative structure approximated the experience of living in Leonard’s head by moving backward, offering discrete chunks of his experience that made no sense until the end of one scene provided context for the one that had come before. It was a clever device, but it was more than that, ultimately serving a story about what we need to believe, or choose not to believe, in order to give meaning to our lives.

In some ways, it feels like Nolan has been chasing that high ever since, trying to give his audience brain-twisting narratives that also leave you with an emotional gut-punch at the end. It’s a tricky proposition, because it’s way too easy for the attempt to come off as grandiose, but he’s mostly managed to find various degrees of success at combining thrilling ticking-clock storytelling with big ideas. He’s always swinging for the fences, yet still somehow manages to be a contact hitter.

All of which brings us to Tenet, and to something where attempting an in-depth synopsis would prove both annoying to Nolan fans wishing to enter cold, and deeply frustrating considering its ultimate direction. Suffice it to say that an unnamed Protagonist (John David Washington), a highly-trained government agent, survives a dangerous mission to be recruited into a top-secret program. He knows only that those in the know identify themselves to one another through the code-word “tenet,” and that the very fate of the world hangs in the balance.

On some level, Tenet works simply as Nolan’s distinctive spin on a James Bond or Mission: Impossible plot, full of exotic locations, eye-popping stunts and villains with grandiose plans (in this case, Kenneth Branagh doing some uncharacteristic underplaying as a Russian arms dealer). Nolan has grown more savvy as an action director over the years, constructing sequences with a solid sense of geography and consequence, even when your head may hurt while trying to put the logic of it all together. Even if it had nothing going for it but its set pieces, Tenet would be a pretty satisfying piece of popcorn entertainment.

We know Nolan well enough by now, however, to realize that he’s not going to leave things on that level. He certainly wants to give things an emotional kick, primarily through the character of Branagh’s long-suffering wife (Elizabeth Debicki) and her frustrated attempts to stay connected with the child that he uses as leverage over her. Debicki give the role her all, but there’s a problem with her arc feeling completely disconnected from Tenet’s primary storyline. The stature of her role in the proceedings doesn’t quite match her physical stature—though whatever else you might think of the movie, it’s a baller move by Nolan to put the 6’3” Debicki in 3-inch heels.

Instead, Tenet tries to address the entire nature of fate and free will through every conceivable time paradox. The “what’s happening” part of Tenet isn’t actually particularly complicated, in terms of keeping up with where various characters are in its time line; indeed, one of its “reveals” is almost so obvious that it’s kind of ridiculous how long Nolan keeps it under wraps. It simply doesn’t feel nearly as momentous as the future-of-all-humanity stakes and pounding Ludwig Göransson score are pushing us to believe. This filmmaker is constitutionally incapable of crafting a science-fiction adventure willing to embrace its ludicrousness, even when that might be the strongest play.

The result is something that could be light and fleet-footed, except that Nolan resists that tone so fervently. Tenet proves engaging on a moment-to-moment basis, and thoroughly satisfying as a technical piece of filmmaking. It’s also almost terminally heavy, too determined to convince you that it’s important to allow it to be fun. Nolan knows that he can give his crazy ideas a human touch; he might actually grow as an artist if he understood when it’s okay simply to lean into a crazy idea.