***SPOILERS*** In trying to help out a 17 year old Sally Jordan, Alexandra Wilson, a runaway from the great state of Michigan who took up hooking to support herself Mike Hammer, Stacey Keach, not only gets involved with a number of vicious New York pimps but also a serial killer who's working independently knocking off their employees: Their stable of ladies of the evening. After saving Sally from a life of sin she immediately go back to work for her pimp Slide, Saul Stine, only to be found strangled the next day by the Westside Highway in Manhattan.
Hammer at first confronted by Sally's grieving big sister Luise, Wendie Malick, who threatened to blow his brains out later joins him in finding her sister's killer. That leads to Hammer being attacked by a number of pimps and their muscle only to be helped by out of towner Roger Payton, Harper, who's looking for his wife who's been missing in NYC for the last three months. Checking out police reports Hammer find out that Payton's wife Kristine was found murdered-strangled-off the Westside Highway the same area where Sally was found. Not only that but over a dozen other young women were found dead under the same circumstances and may have been murdered by the same person!
****SPOILERS**** It's Mike Hammer, of course, who finally tracks down the serial killer by using himself as bait to do it. With the lid blown off to who he really is the killer tries to do in Hammer only to find out that he's a bit over his head in his efforts. Ending up getting swashed by oncoming traffic, after falling through a man-hole, as he slipped trying to push Hammer down from it. P.S There's also a cameo appearance by Dr. Joyce, "O'Brother not her again", Brothers as a criminal profiler and TV host who for once gets it right, due to the script not her intuition, who the serial killer may be. That comes as a total shock to everyone, even Mike Hammer, when his identity is finally reviled.