For better and worse, “Tenet” is just a movie. It won’t beat the virus and it won’t single-handedly save movie theaters. It won’t even really blow your mind. But for much of its 150-minute running time, Nolan’s globe-trotting sci-fi riff on the spy thriller will provide a dazzling escape, one dense with singular imagery and intellectual puzzles. And, perhaps most vitally, it will give a cool, brutalist refresher of the movies’ capacity for awe, for imagination, and, yes, for tiresome grandiosity. For the palindromic “Tenet,” it cuts both ways.

Naturally, “Tenet” opens on a crowded auditorium. At an opera house in Kyiv, just as the conductor is raising his baton, a barrage of bullets rings out and masked men take the stage. Outside, a squadron of covert American agents are stirred. They pick a local police patch for their shoulders, and one among them (John David Washington, known only as “the Protagonist” in the credits) maneuvers to rescue a man who sits in a closed balcony. He greets him with the coded phrase “We live in a twilight world.”

As he’s trying to stop bombs from going off in the theater, an odd thing happens. Tussling with one of the terrorists, a bullet seems to fly backward into the gun. After being taken hostage and tortured, he blacks out. When he wakes up much later, he’s told that he’s been released from the CIA and been enlisted in a shadowy organization known as Tenet. The mission goes beyond borders, he’s told. A Cold War — “ice cold” — is brewing. He’s to try to prevent World War III and an apocalypse worse than nuclear holocaust.