After intercepting nerve gas being sold to Chechen terrorists in Minsk, IMF agent Ethan Hunt is determined to prove the existence of the Syndicate, a criminal consortium the CIAdoes not believe exists.
Hunt is captured by the Syndicate at a record shop in London, while their leader, a blond man in glasses, kills the IMF agent stationed there.
Hunt escapes a torture chamber led by Syndicate member Janik "Bone Doctor" Vinter with the help of disavowed MI6 agent and Syndicate operative Ilsa Faust.
In Washington, D.C., CIA Director Alan Hunley and IMF Field Operations Director William Brandt testify before a Senate committee.
The IMF, currently without a secretary in charge, is controversial because of its destructive methods and other misconduct.
Hunley succeeds in having the IMF disbanded and absorbed into the CIA. Brandt, knowing Hunley will try to capture Hunt, warns him to stay undercover.
Cut off from the IMF, Hunt follows his only lead: the man in glasses, later identified as former MI6 agent Solomon Lane.
Six months later, Hunt, still a fugitive living in Paris (luring a CIA team to a decoy safe house in Havana), enlists former colleague Benji Dunn to attend an opera in Vienna, predicting that an assassination attempt will be made on the Austrian Chancellor at the performance, and that Lane will also be there.
The two stop three snipers, including Faust, but the Chancellor is ultimately killed by a car bomb, and Lane is still not found. Faust drops hints of Lane's plan to Hunt before leaving.
After learning the Syndicate is working against "the old world order" by performing several terrorist acts, Dunn stays with Hunt instead of reporting back to the CIA, despite knowing his action amounts to treason.
Hunt, blamed for the Chancellor's death, is pursued by the CIA's Special Activities Division.
Brandt contacts Luther Stickell to find Hunt before the CIA does.
Stickell tracks Hunt, Dunn, and Faust to Casablanca, where they break into and acquire a secret Syndicate file from a secure building.
Faust flees with the data, evading both Hunt and Syndicate members, although Hunt kills the pursuing agents.
Dunn reveals he copied the data onto a second USB drive, as Stickell and Brandt catch up to them.
Faust returns to London and attempts to use the file to quit her mission to infiltrate the Syndicate, but her MI6 handler, Atlee, compels her to continue, whilst discreetly wiping her drive. Meanwhile, Hunt learns that the data is an encrypted British government red box that requires the Prime Minister's biometrics to unlock it. Lane's men abduct Dunn, and use Dunn and Faust to blackmail Hunt into decrypting the data and delivering it to them. Hunt agrees to the ultimatum, despite protests from Brandt.
As part of Hunt's plan, Brandt reveals their location to Hunley.
During a charity auction held in Blenheim Palace near Oxford, Hunley, Brandt, and Atlee take the PM to a secure room to protect him from Hunt.
Brandt has the PM confirm the existence of the Syndicate, a project proposed by Atlee to perform missions without oversight, effectively making the PM "judge, jury and executioner with zero accountability", before Atlee reveals himself as Hunt in a mask.
When the real Atlee arrives, Hunt forces him to admit that he began the Syndicate without permission and that he has been covering up its existence after Lane hijacked the project and went rogue, turning the Syndicate against him and MI6.
With the PM's biometrics, Stickell discovers the file contains access to £2.4 billion in various bank accounts, which would allow the Syndicate to continue their operations unnoticed; Hunt promptly destroys the data.
At the meeting, outside the Tower of London, he tells Lane he memorized the data and offers himself in exchange for Dunn and Faust.
Dunn escapes after the bomb on him is disarmed, while Hunt and Faust are chased through the Tower of London complex by Lane's men.
Faust kills Vinter in a knife fight, while Hunt confronts Lane and lures him into a sealed, bulletproof glass cell where he is gassed unconscious and taken into custody.
Hunley, having witnessed an IMF operation's success firsthand, returns with Brandt to the Senate committee and convinces them to restore the IMF by covering for Hunt and his team.
After the meeting, Brandt congratulates Hunley, who is now the new IMF Secretary.
