Mission: Impossible – Dead Reckoning Part One is a 2023 American spy action film directed by Christopher McQuarrie, from a screenplay he co-wrote with Erik Jendresen. It is the sequel to Mission: Impossible – Fallout (2018) and the seventh installment in the Mission: Impossible film series. It stars Tom Cruise as Ethan Hunt, alongside an ensemble cast including Hayley Atwell, Ving Rhames, Simon Pegg, Rebecca Ferguson, Vanessa Kirby, Esai Morales, Pom Klementieff, Mariela Garriga, and Henry Czerny. In the film, Hunt and his IMF team face off against "the Entity", a powerful rogue AI.

A next-generation Russian stealth submarine Sevastopol employs an advanced AI, activated by a two-piece cruciform key. The AI deceives the crew into attacking a phantom target only to be struck by their own torpedo, killing all aboard. IMF agent Ethan Hunt travels to the Empty Quarter of the Arabian Desert and successfully retrieves a key piece from disavowed MI6 agent Ilsa Faust. He also fakes her death to ensure she survives a bounty placed by an unknown source. Back in Washington, D.C., he infiltrates a U.S. Intelligence Community briefing for Director of National Intelligence Denlinger discussing the AI, known as the "Entity". CIA director Eugene Kittridge states the Entity achieved sentience and can manipulate cyberspace, allowing it to control global defense intelligence and financial networks. World powers compete to obtain the cruciform key to control the Entity, though the exact means of controlling it are unknown.

Revealing himself, Ethan converses with Kittridge and deduces he placed Ilsa's bounty and states his intention to destroy the Entity, knowing they would be considered rogue actors and are participating in a global race. Ethan and his IMF teammates Benji Dunn and Luther Stickell travel to Abu Dhabi International Airport to intercept the holder of the other key piece while evading US agents. During the pursuit, the key piece is stolen by a professional thief named Grace, while Luther and Benji disarm a hoax nuclear device. Ethan suspects foul play after seeing Gabriel, a sadistic Entity liaison with ties to his pre-IMF past. Aborting the mission, the team scatters and Grace escapes to Rome. She is apprehended upon arrival but Ethan rescues her from local authorities, US agents, and an Entity operative named Paris. Grace escapes again, while Ethan rendezvous with Luther, Benji, with Ilsa rejoining them. With Benji and Luther providing support, Ethan and Ilsa follow Grace to Venice where they infiltrate a party held by the arms dealer Alanna Mitsopolis.

With the party masquerading as a brokerage set up by the Entity, all groups disclose their role in acquiring the complete key. Grace was hired by Alanna to steal the other key piece to produce the completed key, which will be sold to her buyer the next day on the Orient Express. Through the Entity, Gabriel proclaims he will possess the completed key the next day and that either Ilsa or Grace will die. Ethan unsuccessfully attempts to dissuade Alanna from the sale, allowing Gabriel and Grace to escape. Ethan pursues Grace, but the Entity hacks into their communications and impersonates Benji, leading him into a fight with Paris, whom he spares. Concurrently, Gabriel incapacitates Grace and kills Ilsa, devastating Ethan, who vows revenge. Thus, Grace agrees to impersonate Alanna and take the key during the sale. Luther leaves for an off-grid location to prevent interference from the Entity, advising Ethan to spare Gabriel to determine information about the Entity. On the train, Gabriel kills the engine crew and destroys the throttle and brake. With Paris, Gabriel meets Denlinger, who divulges information only he knows in an attempt to form an alliance between himself and the Entity.

Originally an advanced cyber weapon developed by the US, the Entity went rogue following its deployment against the Sevastopol. The completed key unlocks a chamber inside the vessel containing the Entity's source code, allowing it to be destroyed or controlled. Gabriel subsequently kills Denlinger and tries to kill Paris as the Entity determined she would betray them after Ethan spared her life. Impersonating Alanna, Grace brings the key to Kittridge, revealed to be the buyer, and negotiates a $100 million sale alongside protection for herself, but pickpockets the key from Kittridge after cancelling the transfer. Ethan parachutes into the train to save Grace, but Gabriel acquires the key. Ethan and Gabriel fight atop the train, but Gabriel escapes and detonates a bridge ahead. Grace and Ethan detach the locomotive from the rest of the train, saving the passengers. Paris rescues both from falling and manages to tell Ethan the key's connection to the Sevastopol before losing consciousness. Grace informs Kittridge of her desire to join the IMF. Ethan flees the wreckage by paraglider with the completed key, which he took from Gabriel during the fight, and rendezvous with Benji to continue the mission of finding the Sevastopol and destroying the Entity.