Jimmy Lait (Brown) and his girlfriend, Wendy, come across Jimmy's friend, House, wounded and dying. Lait learns from House that he had escaped from a secret medical experimentation facility. Later in the hospital, a delirious House tells Lait that there is someone who aims to "kill us all" and that they have a way of doing it. However, Lait has to return to the studio to supervise a recording session with a group he's producing, The Impressions. He leaves Wendy in the hospital.
While Wendy talks to Jimmy on the phone outside of the room, two men climb through the window, assassinate House and kidnap Wendy. After finding out about her kidnapping, Jimmy begins a quest to find the whereabouts of his girlfriend, but a group of attackers ambush him. Lait survives with the help of his friend, Jagger Daniels (Williamson). Lait and Daniels join up with Mister Keyes (Kelly, named "Mister" by his mother so people would be forced to show him respect) after he wins a fist fight with several police officers attempting to plant drugs in his car.
Lait is shot as they capture a member of Feather's gang, but are unable to force him to give up his secrets. Jagger calls three dominatrixes: The Countess (Pamela Serpe), The Empress (Irene Tsu), and The Princess (Marie O'Henry). The eager women ask Jagger if they can go all the way, meaning, torturing the captured man to death. Jagger tells them, only after the prisoner gives him the information he seeks. They agree and proceed to go upstairs to torture the tied up man. The three women at first excite the captive by baring their breasts, but they torture him while Keyes and Daniels wait. After some time the women emerge, and say the captive is ready to talk. He informs them of Feather's plot and dies from his torture.
There is a secret plot of black genocide concocted by the nefarious Monroe Feather (Jay Robinson), the leader of a secret Neo-Nazi, white supremacist organization. Their chief scientist, Dr. Fortrero (Richard Angarola), has developed a lethal poison that only affects African Americans. They plan to deploy the serum into the water systems of Washington D.C., Detroit, and Los Angeles, in order to wipe out their black populations.
The three heroes re-unite as Lait is leaving the hospital, and decide to stop the poisoning of the water supplies. "Three the hard way, three cities, the three of us."
Lait returns to Chicago. Mister Keys stops the poisoning in Washington D.C., as Jagger does in Detroit. They reunite again to stop Feather and arm themselves to the teeth. They raid Feather's compound and rescue Wendy after a huge shoot out, leaving Dr. Fortrero burned alive, Feather and many white supremacists dead.
Along with director Gordon Parks Jr.'s other notable film Super Fly, Three The Hard Way had a lesser, but still substantial, effect on popular culture.
The plot of Three The Hard Way has been copied and parodied, most notably in the film Undercover Brother. In Undercover Brother, protagonist Eddie Griffin portrays "Undercover Brother", a soulful crime-fighting vigilante who must stop the white-run "Man" before he destroys the black population of the United States through an ingested toxin. Also, the Man's second in command is named Mr. Feathers, played by Chris Kattan, who is named after Monroe Feather from Three The Hard Way.
Black Dynamite, a satirical parody of the blaxploitation genre, contains quite a few plot elements reminiscent of Three the Hard Way. The title protagonist (played by Michael Jai White, is a kung-fu master, and the plot revolves around a malt liquor tainted with ingredients that shrinks black men's genitalia.
Performed by Curtis Mayfield's former group The Impressions, the soundtrack featured the songs "That's What Love Can Do" and "Three the Hard Way" plus "Make a Resolution". The album got mixed reviews from critics and was described as "quickly recorded with little feel". Most of the songs feature a sweet-sounding harmony over a light funk background.Jim Brown as Jimmy Lait, record producer
Fred Williamson as Jagger Daniels, Chicago businessman
Jim Kelly as Mister Keyes, martial artist
Sheila Frazier as Wendy Kane, kidnapped girlfriend of Jimmy Lait
Jay Robinson as Monroe Feather, head of white supremacist group
Charles McGregor as Charlie
Howard Platt as Keep
Richard Angarola as Dr. Fortero
David Chow as Link
Marian Collier as Eva
Junero Jennings as House
Alex Rocco as Lt. Di Nisco
Corbin Bernsen as Boy
Renie Radich as Girl
Janice Carrol as Nurse
Irene Tsu as the empress