Diamond Dog arrives in Vacaville, CA with many other separatees destined for a supermax facility in Mobile, AL. As he leaves the transfer bus for the plane, his criminal record is briefed by U.S. Marshal Vince Larkin. Diamond Dog was a general in a black supremacist military group known as the Black Guerillas. He was found guilty of blowing up a meeting of National Rifle Association members, claiming "they represented the basest negativity of the white race." During his incarceration he wrote a book titled "Reflections in a Diamond Eye", which was reviewed by the New York Times as "a wake-up call for the black community." Apparently, the book also attracted the attention of Hollywood for a film production, with the possibility of starring Denzel Washington in the lead role.
Unknown to the guards, Diamond Dog is part of a plot to take over the plane and escape to a non-specified South American country, free of extradition. The master conspirator with Diamond Dog is fellow separatee convict Cyrus "The Virus" Grissom. When the Jailbird leaves Vacaville, Diamond Dog breaks free of his handcuffs thanks to a small pin imbedded in his hand. After fellow conspirator "Pinball" Parker instigates a fire, the guards rush to contain it, allowing Pinball to steal the keys to Diamond Dog's cell and release him. He immediately kills a guard (Bobby Chambers) with one end of his handcuffs, but is tazered by the other guards. However, Grissom also is released and seizes the only firearm on board, taking control of the plane.
Dragging a dead guard across the blood-soaked floor of the plane, Diamond Dog laughs at how heavy the "pig" weighs. He and Grissom then explain to the other convicts that cooperating with them will ensure a life of freedom and luxury under the provision of fellow convict Francisco Cindino, awaiting them in Carson City, NV. While Diamond Dog desires to kill the surviving guards, Grissom plans to use them as substitutes for the expected transfer. Diamond Dog and others (Cyrus, Billy Bedlam, Johnny 23, and Pinball) disguise themselves as guards upon arriving at Carson City.
The transfer goes as planned, but unbeknownst to the criminals, a U.S. Army Ranger parolee, Cameron Poe, is also aboard the plane, expecting to fly home to his wife and daughter. Poe plants evidence of the plane's takeover on Falzon, one of the transferred guards, alerting the authorities. The Jailbird escapes capture and resumes course to Lerner Airfield, where Cindino is expected to fly everyone to freedom. During the flight, Diamond Dog appears to strike up a friendly conversation with Poe, humorously nicknaming him "Hillbilly", inquiring what's on his mind. Poe questions why Diamond Dog was allowing Grissom to take charge, to which Diamond Dog confides in Poe that he's just playing along until they arrive at Lerner, where he'll assume command of the escape.
Diamond Dog is also ordered by Grissom to investigate why the plane is not maintaining full speed. He in turn orders Poe to accompany him to the plane's belly where the landing gear is located. They discover Pinball, thought to be left behind in Carson City, having been crushed to death by the plane's tire. With Diamond Dog's back turned to Poe, the latter hastily scribbles a message on Pinball's shirt to inform the police of their destination before dropping the body, and is almost noticed by Diamond Dog, who sarcastically bids farewell to Pinball.
Upon arriving at Lerner Airfield, Diamond Dog is about to kill the remaining guards, when he is stalled by Poe, who argues that they will need hostages. Furious, Diamond Dog threatens Poe, as well, but is stopped by Grissom, who agrees with Poe, and orders Diamond Dog and the other convicts to prepare the plane as a backup plan. When Cindino is killed by Grissom for attempting to leave them behind, Diamond Dog appears shocked at Grissom's sadistic manner of murdering Cindino, but joins with him to engage an arriving team of police and SWAT Team members.
A fierce firefight breaks out between the two factions, forcing the convicts to flee in the Jailbird. Having escaped once more, the convicts celebrate, until Diamond Dog brings a child's letter to Grissom, identifying a "traitor" among them. Before Poe can confess to opposing the convicts' plans, the plane is attacked by military helicopters, forcing the plane to crash land in Las Vegas, NV.
Diamond Dog, along with Grissom and Swamp Thing, are the only three to evade capture. Stealing a fire truck, they are pursued by Poe and Vince Larkin. Despite Diamond Dog's attempts to kill both pursuers, Poe rams his motorcycle into the fire truck, causing an explosion and killing him.
Diamond Dog, like Billy Bedlam, Garland Greene, and Cyrus "The Virus", is one of the most dangerous convicts in the movie. A black supremacist, he strongly despises white people (he has murdered people for simply being white, making him the most biased character in the movie), but he is willing to work with them in order to further his own goals. He strongly despises authority, desperately wanting to kill the "pigs" immediately, getting frustrated easily when Poe and Cyrus stop him from doing so. It is shown that he has contempt for Pinball and Baby-O, despite them being black, as they do not share his black supremacy beliefs. Despite his cruel and violent nature, he is afraid of Garland Greene (due to the atrocious nature of his killings) and Cyrus "The Virus" (due to Cyrus killing Cindino for betraying him).