Tenet Ending Explained

Christopher Nolan's Tenet is complicated. REALLY complicated. Our resident expert picks apart the multitude of different threads.

John David Washington in Tenet
Photo: Warner Bros.

Contains spoilers for Tenet from the start

In some ways it feels a bit unfair that the film that is supposed to bring everybody back to the cinema is one that you have to watch twice, possibly once backwards, to understand the plot.

Even more than Nolan’s other work, Tenet is a film of clockwork-plotting, non-linear storytelling and the feeling that if you blinked at some point you’ve now missed essential elements of the plot.

Luckily, we’re here to talk you through the complicated bits, point out the bits you might have missed, and generally give you everything you need to authoritatively explain what happened, to your friends who also didn’t understand it.

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What is the Algorithm?

By the final act we’ve discovered that the bits of nuclear weapon the Protagonist has been finding and losing throughout the film are part of something called “the Algorithm”, which is the MacGuffin everybody is chasing.

To be honest, all you really need to understand in the context of the movie is that it will end the world unless the good guys find it in time, but if you want your understanding to go a little deeper than that, it is a formula that will allow the Enemy to invert entropy on a global scale – basically reversing the flow of time worldwide.

The scientist who developed this formula immediately realised this wasn’t a good thing to have invented, and so she “inverted” each part of the Algorithm, sending them back in time to different places so it can’t be used.

What’s Sator’s plan?

Sator, who has been in correspondence with people in the future, has been charged with tracking down each part of the Algorithm and putting them together. Once all the parts are assembled his plan is to put them in a “Dead Drop” (a fancy spy way of saying “leaving it somewhere for someone to find later”). Specifically, the Algorithm will be dropped into a pit underneath Sator’s own nuked hometown at the instant he dies (triggered by his pulse dropping to zero on his Fitbit).

When that happens (and we’re stretching the meaning of the word “when” here) it will be found by the faction in the future, who will then use it to reverse time because, frankly, we’ve messed the planet up so much they don’t want time to keep moving forward any more.

At this point time will be trying to run forwards and backwards at the same time, and so all of history will get chewed up like a cassette in a cheap Walkman, instantly destroying everyone and everything that ever was.

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How did the Tenet organisation plan to stop this?

The Tenet organisation’s plan to stop the cessation of all time was to send two armies, a backwards travelling one and a forward travelling one, to the dead drop site at the same time to snatch the Algorithm before it could be dropped into the pit, then break it up into little pieces and a hide it again.

To stop Sator from going back even further to stop them from stopping him, they have to do this right before Sator dies.

Yeah, about that, how can Sator die if we see him alive in the future?

Sator has a terminal illness and knows he will die, and so decides to do it on his terms (and also kill everyone else at the same time). Having alienated and then murdered his wife, and having access to a time machine, Sator decides that the moment he would like to die is the last time he and his wife were happy.

From his perspective, during that holiday in Vietnam his wife was in love with him, he made an offer to set her free in exchange for never seeing her son again, she got angry and he left. So for his last moments on Earth he travels back to that holiday, returns to his wife to kiss and make up, and then he’ll die in her loving embrace.

From Kat’s perspective, she and her son left for the island after Sator made that offer, and when she came back she saw a mysterious woman dive off their boat (who she assumed was Sator’s mistress). Later, after Sator shot her, she healed, also travelled back in time to that holiday, pretends to be the Kat from that time, then kills him and dives into the water so her past self can see her.

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When did the Protagonist recruit Neil?

One of the tertiary mysteries of Tenet is the question of who recruited Neil to the organisation. And by “mystery” I mean that as soon as the Protagonist asked Neil who recruited him everyone who’d ever seen a time travel movie shouted, “You in the future did!”

Sure enough, when we see the airport heist from the inverted perspective, we see Neil unmask the Protagonist, and presume that this is when the Protagonist draws him into the Tenet organisation.

But at the end of the film, as Neil goes back into the battle to save the Protagonist, revealing the orange tag on his bag that shows he was the soldier who died rescuing the Protagonist during the film’s climax, as well as the soldier who saved him during the Opera House fight scene at the start of the film, he reveals that he was actually recruited far earlier.

Which leads us onto Tenet’s final reveal…

Does the Protagonist now run the entire Tenet organisation?

At this point the Protagonist has inferred that not only does he go further into the past and recruit Neil, but that he goes back and founds the entire Tenet organisation in the past, recruiting all of its operatives, including, indirectly, himself.

He does this while also managing to turn up at any point in Kat’s future when she might be in danger.

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Given that he can only move forwards or backwards in time at a rate of one hour per an hour, this must involve some absolutely pristine scheduling and a lot of premature aging. We really want to see his personal organiser.

Isn’t calling your main character “the Protagonist” a bit too painfully meta?

I know right?

Tenet is out now in UK cinemas