This is one of those movies everybody should see if only for that chase scene, the father of all chase scenes.
Roger Ebert describes the plot this way:
McQueen plays a San Francisco cop assigned as bodyguard to a syndicate witness. The witness gets shotgunned -in the most brutally direct 10 seconds of film I can remember- and McQueen becomes a political football. Robert Vaughn (better than usual) is the politician who puts the heat on, and it's up to McQueen to hide the victim's body until he can untangle the case.Rotten Tomatoes has a critics rating of 97%. Empire Online concludes: "Stlick, stylish and ineffably cool, this was perhaps McQueen's defining role. Also mention goes to the uncreditied star of the film; San Francisco."
It's a very tangled case, too. The beautiful thing is that Yates and his writers keep everything straight.