Tenet Plot

A CIA agent, the "Protagonist", participates in an undercover operation at a Kyiv opera house. His life is saved by a masked soldier with a distinctive red trinket, who "un-fires" a bullet through a hostile gunman. After seizing an artifact, the Protagonist is captured by mercenaries. He endures torture before consuming cyanide. He awakens to learn the cyanide was a test of his loyalty; his team has been killed and the artifact lost.

The Protagonist is employed by a secret organization called Tenet. Their scientist shows him bullets and other objects with "inverted" entropy that allows them to move backwards through time. She says they were made in the future (“the detritus of a coming war”), and a weapon exists that can wipe out the past. Aided by a local contact, Neil, the Protagonist traces the bullets to arms dealer Priya Singh. He discovers she is a member of Tenet; her bullets were purchased, and then time-inverted, by Russian oligarch Andrei Sator.

The Protagonist approaches Sator's estranged wife Kat, an art appraiser who unknowingly sold Sator a forged Goya drawing. Sator uses the drawing to blackmail her and keep her under his control. The Protagonist plots to steal the drawing with Neil from a free port facility in Oslo Airport. There, they find a machine, a "turnstile", and fend off two masked men. Priya explains that the turnstile can invert the entropy of objects and people, and the masked men were the same person: one inverted and one normal.

In the Amalfi Coast, Kat introduces the Protagonist to Sator, but learns the drawing is intact. The three go boating and Kat attempts to drown Sator, but the Protagonist saves him. The Protagonist offers to help Sator retrieve a case he says contains Plutonium-241. In Tallinn, the Protagonist and Neil ambush an armoured convoy and steal the case, which contains the artifact lost in Kyiv. They are ambushed by an inverted Sator, who holds Kat hostage. The Protagonist gives Sator an empty case and he retreats. The Protagonist saves Kat, but is captured and taken to Sator's warehouse.

The inverted Sator shoots Kat with an inverted round, while the normal Sator demands the location of the artifact; the Protagonist gives him false information. Tenet operatives led by Ives rescue the Protagonist while Sator escapes. The group take Kat through Sator's turnstile to invert her, reversing the effect of the round. The Protagonist returns to the ambush site and chases Sator. His vehicle is overturned and Sator sets it on fire; the Protagonist is saved by Ives' team again. Neil reveals he is a member of Tenet.

The Protagonist and Neil travel back in time to the free port in Oslo. There, the Protagonist (revealed to be the two masked men that he and Neil earlier fought) fights his past self and enters the turnstile to revert himself, followed by Neil and Kat. Priya explains that the artifacts are parts of an "algorithm" Sator is assembling, capable of catastrophically inverting entropy.

Sator square provides the film title, location of the opening sequence (Kyiv Opera), and character or firm names (A. Sator; Arepo the Goya forger; and Rotas Security in Oslo Freeport).^[6]

Kat reveals Sator is dying from pancreatic cancer. He will trigger the algorithm with a dead man's switch, believing the world should die with him. Kat believes Sator will kill himself during their vacation in Vietnam when they were last happy together. The Protagonist, Neil, Kat, and the Tenet forces invert back to that day so Kat can delay Sator's death while Tenet secures the algorithm.

Tenet tracks the assembled algorithm to Sator's hometown of Stalsk-12 in Northern Siberia. In a "temporal pincer movement", red team troops move forward in time, while the blue team troops move backward. The Protagonist and Ives are aided by a masked corpse of a blue team trooper with a trinket on his backpack after seeing him dying in reverse. In Vietnam, Kat boards Sator's yacht and kills him as the Protagonist and Ives secure the algorithm.

The Protagonist, Neil, and Ives break up the algorithm and part ways. The Protagonist notices the red trinket on Neil's rucksack. Neil reveals he was recruited by the Protagonist years earlier from his perspective, but years from now from The Protagonist's perspective, and this mission is the end of a long friendship for Neil, but for The Protagonist, it was the beginning. Priya attempts to have Kat assassinated, but is killed by the Protagonist, who has realized he is the future mastermind behind Tenet.