The 1968 film "Bullitt" is about a San Francisco police dedicated who is assigned as a bodyguard to a mafia informant. When the witness is killed, Bullitt, played by Steve McQueen, must hide the body until he can crack the case.
Bullitt and two others are tasked with protecting the witness until an ambitious politician can present him to a Senate crime committee as a way to further his own career. The politician, played by Robert Vaughn, keeps the pressure on, hoping to score a political victory.
When the witness is shot and killed, Bullitt's concern is with capturing the killer. His supervising officer allows him to investigate the case independently. Meanwhile, the politician enlists the help of another police detective to take Bullitt down.
"Bullitt" is famous for a chase scene through the hills of San Francisco in which Bullitt alternately pursues and is pursued by a pair of gangsters. McQueen himself did the driving for the iconic scene.
Bullitt also has a love interest played by Jacqueline Bisset. Famed critic Roger Ebert, however, has opined that the romantic subplot adds nothing to the movie. Like the chase, the film has some twists and turns, but Ebert praised the movie for not becoming too convoluted.