'Sudden Impact' is the fourth film in The Dirty Harry Series. There were five films in all. If you decide to watch them again, or even for the first time, be sure to watch them in order.San Francisco Police are searching for a vicious serial killer. They trace a link to a small town further down the coast. When Harry Callahan upsets the Mayor and the press in his usual style, he gets shipped out to investigate when the heat is  on. While doing so he leaves behind his usual trail of dead criminals along the way.