Red Crow, a Lakota medicine man, and his two sons Hank and George Storm, are entrusted with transporting a sacred lance to be displayed at a Philadelphia, Pennsylvania, museum. The medicine man warns Hank and George that, only as long as the lance belongs to the Lakota, will they survive as a people. Undercover policeman Buster McHenry is drinking at a bar when he sees two patrolmen stop a carload of gang members. As more police arrive, a thug draws his pistol, attempting to take a hostage. A standoff occurs, until Buster feigns drunkenness and holds the gangsters at gunpoint. Unaware of Buster’s status, the police arrest him. At the station, Lieutenant Mike Finch releases Buster from the “drunk tank” and warns him about running his own operation. Buster pleads ignorance, but hints that he has uncovered police corruption. He meets with gangster Bobby Marino to discuss stealing $2 million worth of diamonds. Buster is frustrated upon learning that a bookkeeper will supply the safe combination, rather than the officer under investigation. During the robbery, Marino shoots the bookkeeper to silence him. Police arrive before the thieves can escape, and one is shot in an alley. Buster, Marino and a gangster named J. J. take refuge in the art museum displaying the sacred lance. George Storm protests and Marino shoots him in the chest. Buster pulls his gun on Marino, but is pistol-whipped by J. J. Marino steals a car and forces Buster to drive, with police in pursuit. Following a harrowing chase, Buster drives into an empty quarry, where Marino shoots the detective in the back and leaves him for dead. Hank arrives in a stolen sports car and begs Buster not to die until he retrieves the lance. He takes Buster to a flophouse and removes the bullet, then asks Red Crow to perform a healing ritual. The next day, Marino learns that Buster is a policeman and orders J. J. to have him killed. Hank returns to the hotel to discover two hired killers, whom he evades by taking Buster to another room. Later, Buster tells Hank that he is a police detective working undercover to learn the identity of an officer on Marino’s payroll. Red Crow breaks his medicine stone in half and gives a piece to Hank to aid him in locating his brother’s killer. Hank and Buster drive to his apartment to get weapons, only to find it surrounded by police. After stealing guns from a pair of drug dealers, Hank and Buster are pursued by a young officer, but the Lakota overpowers him. Lt. Mike Finch informs Captain Blaloch of the incident, and a warrant is issued for Buster’s arrest. Buster and Hank kidnap Corso, one of Marino’s henchmen, and force him to reveal his boss’s whereabouts. Marino and Finch are at the gangster’s ranch when they receive word that Buster is searching for him. Finch berates Marino for his poor handling of the situation, and insists on dealing with the detective. Following a tip from Corso, Hank and Buster question Marino’s girl friend, Barbara, but she refuses to divulge her lover’s location. They are quickly surrounded by Marino’s gunmen and escape with Barbara. After finding refuge in a subway station, Buster insists that Hank allow him to take Marino alive. Hank refuses, prompting Buster to push him onto a train. Undaunted, Hank follows Buster and Barbara into a department store. The Lakota is detained by security guards, and Buster pretends to arrest him. Finch attempts to question Red Crow, but Marino and his men interrupt, threatening the medicine man. Red Crow responds by hurling a knife at Marino. A henchman steps in front of the oncoming knife, while others shoot Red Crow. A short time later, Hank arrives to find his father’s body holding the other half of the medicine stone. As he, Buster, and Barbara leave, Marino shoots his girl friend in the head. A gunfight erupts, and Marino flees at the sound of police sirens. Hank and Buster are arrested, and Finch orders them placed in his car, where they are joined by Detective Ransom. Buster recognizes the car as belonging to one of Marino’s men, and tells Finch that he is close to recovering the stolen diamonds, worth $6 million, rather than the $2 million reported to police. Over Ransom’s protests, Finch releases Hank and Buster after they promise to bring him the diamonds. Later, Ransom informs Finch that he is also on Marino’s payroll. They drive to the gangster’s ranch, with Buster and Hank in pursuit, unaware that they are being lured into a trap. As they arrive at the ranch, Marino hides in the bushes with his men and the rogue policemen. Hank and Buster attack two guards and take their shotguns. A gunfight erupts, forcing Hank and Buster to take cover in the barn. While J. J. shoots flares into the hayloft, Hank escapes on horseback and retrieves the lance. Buster commandeers a motorcycle and drives it directly into Det. Ransom. Lt. Finch jumps out from behind a tree and Buster shoots him with his last bullet. Before Finch can return fire, Marino guns the detective down. As the gangster aims at Buster, Hank rides to his friend’s aid, but he is intercepted by J. J. Marino fires, inadvertently killing his henchman. Buster retrieves the lance and hurls it into Marino’s chest. Weeks later, Buster visits Hank’s reservation to thank him for his assistance.