Lieutenant Frank Bullitt, a seasoned San Francisco police officer, is entrusted with a seemingly routine assignment: to protect Johnny Ross, a star witness set to testify against the mob before the Senate subcommittee on organized crime. Anticipating a high-profile case that could significantly boost his political career, ambitious politician Walter Chalmers selects Bullitt for this sensitive task, expecting flawless execution. Bullitt and his team set up a safe house to secure Ross over the weekend before the committee hearing. The operation starts smoothly, but in the dead of night, two hitmen locate the hideout and shoot Ross, leaving him in critical condition. Simultaneously, one of Bullitt's team members is gravely wounded during the attack.

Determined to uncover the perpetrators, Bullitt begins his investigation, asking his superiors for additional time to delve deeper before they remove Ross's protection detail. Navigating a labyrinth of lies and deceit, Bullitt finds inconsistencies in Ross's story. Suspecting that there's more to Ross's identity and his involvement with the mob than initially believed, Bullitt continues his relentless pursuit across the city. The situation intensifies as Chalmers pressures Bullitt for results, creating a tense power struggle between the two men. As Bullitt pieces together the clues, his dedication to the case takes him through San Francisco's gritty underbelly, culminating in a high-speed car chase that pits him against the deadly hitmen in a race against time.