The first in the series of films featuring Lieutenant Harry Callahan (Clint Eastwood) - a right wing, bad-tempered San Francisco policeman, not averse to bending the rules to get his man. The maniacal 'Scorpio Killer' is on the loose and Callahan disregards procedure in his efforts to track him down, using his trusty Magnum .44 to dispense his own brand of justice.