Harry Callahan (Clint Eastwood) has little regard for the law, preferring his version of justice instead. He famously wields a .44 Magnum which he uses with devastating accuracy, and his partners rarely last longer than the criminals he brings to justice.
Scorpio (Andy Robinson) is a new serial killer in San Francisco shooting random victims and demanding a ransom of $100,000 to stop. It's a game of Cat and Mouse between Callahan and Scorpio and only one is likely to survive.
Harry Callahan himself, as a character, brought fame to the ambiguously good cop theme with Eastwood's array of famous quotes that teased the criminals while they submitted. This character - and thus Eastwood who plays the part superbly, is the sole reason for the movie's success as the rebel-against-the-system in everyone comes out to play.
The plot may be slightly thin on the ground, but it can be easily followed for the casual movie-goer, and equally be pulled apart and analysed for anyone wishing to study the film in closer depth for its conflict of good vs. evil - even just in the protagonist.
Despite being an early contender into the cop film revolution, it is still one of the top films and for a movie that ticks all the boxes, it's certainly one that is difficult to top.