On a date called "the 14th", the Protagonist leads a covert CIA extraction during a staged terrorist siege at a Kyiv Opera House. He is saved from KORD by an oddly behaving operative with a red trinket. The Protagonist retrieves the artifact but his team is sabotaged, captured, and tortured. He swallows a suicide pill but wakes up to find it was a fake; a test that only he has passed. Recruited by a secretive organization known as "Tenet", they brief him on bullets with "inverted" entropy that move backwards through time. With his handler Neil, he traces them to Priya Singh, an arms dealer in Mumbai. Priya reveals she is in Tenet and that her bullets were inverted by Russian oligarch Andrei Sator, who is communicating with the future. Sir Michael Crosby advises they approach Sator's estranged wife Kat Barton, an art appraiser who authenticated a forged Goya painting that Sator purchased from her friend Arepo, which he now uses to blackmail her.

Ovi Mahajan – son of an incarcerated Indian drug lord Ovi Mahajan. Sr – sneaks out of his house to visit a club with his friend. At the party, Ovi and his friend go to the garage to have a smoke, where they encounter corrupt police officers working for rival drug lord Amir Asif, who shoot Ovi's friend and kidnap him. After discovering this, Saju Rav, a former Para Lt. Colonel and Ovi's protector, visits Ovi's father in prison. Unwilling to pay the ransom or surrender his territories to Amir as it will hurt his prestige, Ovi's father orders Saju to retrieve his son, threatening to kill Saju's own son if he is unwilling to do so. Tyler Rake, a former SASR operator turned black-market mercenary, is recruited by his handler Nik Khan, to save Ovi from Dhaka, Bangladesh.

After a meeting between the Torricelli Sicilian Mafia crime family and black market dealers, Massimo Torricelli watches a beautiful woman on a beach and talks with his father, the mafia boss. Suddenly, the dealers shoot Massimo and his father; Massimo survives while his father dies from his injuries. Five years later, Massimo is the leader of the Torricelli crime family. In Warsaw, Laura Biel is unhappy in her relationship with her boyfriend, Martin. Laura celebrates her 29th birthday in Italy with Martin and her friend Olga, but after Martin visits Etna without her, she goes for a walk and runs into Massimo, who kidnaps her. At his villa, Massimo reveals to Laura that she was the woman at the beach five years ago and that when he was injured, all he could think about was her. After searching for years and finally spotting her, he kidnapped her, intending to keep her as a prisoner for 365 days in the hopes that she will fall in love with him. He also promises her that he will not touch her intimately without her consent while he is physically and sexually aggressive towards her.

Isabel Aretas, widow of drug kingpin Benito, escapes from a Mexican prison with the aid of her son Armando. Isabel sends Armando to Miami, tasking him with recovering a substantial stash of money his father Benito had hidden, as well as assassinating the people responsible for his father's arrest and eventual death in prison. Isabel demands that Armando should also kill Detective Mike Lowrey, who is settled in Miami. Mike accompanies his partner Marcus Burnett to the birth of his first grandson. Desiring to spend more time with his family, the aging Marcus tells Mike he intends to retire, to Mike's chagrin. During a party celebrating Marcus's grandson, Mike is shot by Armando and left in a coma for months. Chastised by Isabel for targeting Mike first, Armando continues to assassinate other targets on his list during Mike's convalescence.