When homicide detective Stanley Bentworth fires his weapon in the line of duty for the first time, he kills a youth from the projects. The tragic event pulls at his conscience, and he deals with Internal Affairs (the "rat squad"), a city psychiatrist, and outraged citizens.
On administrative duty pending the investigation, he infiltrates Narcotics to ferret out corrupt cops. But the Lieutenant sends him undercover on the street to ferret out an enigmatic drug kingpin, and Stanley must do battle with the rat squad, dirty cops, outraged citizens, and gangbangers.