A vicious serial-killer is on the loose in San Francisco and the police trace a link to the small town of San Paulo, which is further down the coast. When Harry Callahan (Clint Eastwood) upsets the press and the Mayor in his usual style, he's shipped out of town to investigate while the heat is on. With the help of his new .44 Magnum "AutoMag" handgun, Harry goes on the trail leaving behind the usual trail of dead criminals along the way.