"A Perfect World," ostensibly about the escape of convicts Butch Haynes (Kevin Costner) and Terry Pugh (Keith Szarabajka) from a Huntsville prison, quickly focusses on their hostage-taking of an 8-year old boy, Philip Perry (T. J. Lowther). The movie opens with the final scene, Butch lying in a field with a Casper the Friendly Ghost mask lying beside him in the grass, a helicopter hovering, and money blowing in the breeze. Both the man and the mask have a faint smile on their faces. The rest of the movie answers the questions posed by that enigmatic opening image.
In a small town somewhere in Texas, the town kids are trick or treating except for one family sitting at the kitchen table talking about Halloween. The mother, Gladys Perry (Jennifer Griffin), explains that their religious beliefs put them on a higher plane where such activities are forbidden. Just then the doorbell rings and some children outside yell "trick or treat." Gladys answers the door and explains they don't participate in the holiday because they are Jehovah's Witness.
Meanwhile, Larry Billings, a prison guard, returns to the prison to get some paperwork to do at home even as the two prisoners in their cells (Butch and Terry) consult with an elderly inmate regarding where the vents go. Once Butch and Terry break through the vents, and it is clear that an escape is underway, Butch tells Terry that they will separate when they get free and reach the state line because he doesn't like Terry. And Terry agrees with that plan as their hatred for each other coalesces. Butch and Terry get past the guard at the gate in Larry's car with Larry at the wheel. Once they reach town they commandeer Larry's car and search for a new escape car. Terry is sidetracked by Gladys making breakfast. Terry breaks into the kitchen holding a gun and terrorizes her, grabbing her around the neck for a smooch. Young Philip, who has wandered in, gets on Terry's nerves so he slaps the boy, an action that further infuriates Butch and precipitates a struggle between the two. Butch asks Philip to pick up the "Pistola" and give it to him. Then Butch says to point it at him and say "stick em up," a make-believe playful act, but deadly serious, which he does. A neighbor tries to save the family but Buzz asks him to drop the rifle because he might hit the boy and the neighbor agrees, a pattern of negotiation and violence avoidance that continues throughout the movie. Butch and Terry take the boy, Philip, as a hostage and leave, still in the guard's car.
At the state office of the Texas Rangers, Red Barnett (Clint Eastwood) speaks with the Governor by phone. Sally Gerber (Laura Dern), criminologist from Huntsville hired by the Governor to assist Red in matters concerning parole and escapes, introduces herself to Red as one of the team, a fact that does not sit well with Red. The Governor also loans Red's team a shiny new truck and trailer to track the escapees. The rig has lots of bells and whistles and looks suspiciously like a Campaign Headquarters on Wheels with its decorative bunting. While loading up the new trailer prior to starting the manhunt, FBI agent Bobby Lee (Bradley Whitford) is added to the team and Sally is almost left behind.
Meanwhile, the escapees and their young hostage are trying to find somewhere to hide out. Terry looks for his cousin's name in a phone book while keeping an eye on Butch and threatening him. Butch responds by breaking his nose. They stop at a store for provisions and Butch asks Philip to train the gun on Terry to hold him in check while Butch shops. Terry starts to play with Philip and try to get the gun away, and resorts to intimidating Philip physically and verbally by casting aspersions on Philips manhood ("Kind a puny, ain't it?"). When Terry grabs Philip, Philip bites his hand and runs to hide in a corn field across the road, maintaining possession of the gun. Terry searches for Philip even as Butch sees his traveling companions are missing. Butch locates Philip first in the corn field and Philip returns the gun to Butch. Butch shoots Terry. As Butch and Philip get back to the car, the store owner emerges from the store with a rifle but Butch tells him to go lie on the floor of the store until they leave.
As the truck and trailer head down the road Red's manhunt team learns about the sighting of the escapees. Sally tells Red they need an auxiliary roadblock because the prisoners will split up. Only one road block is set up. Red and Sally argue about her spot on the team. Red informs her that a strong back side and a sense of humor are the only prerequisites to serving on his team. Sally explains that she is not a moron, she just wants to do her job. Red says that he is in charge and takes responsibility but agrees to listen to her concerns.
Butch and Philip continue on as running buddies, drinking RC Cola and getting to know each other. Butch appeals to the boy's desire to play by telling Philip that the car is a time machine and they are driving into the future. He explains gas and brake pedals and that they need to find a Ford to steal.
Terry's body is found. Red's entourage continues to follow the escapees.
Butch and Philip find a Ford. Butch has Philip play "like an Injun" and check whether the keys are in the ignition and whether there is a radio. Yes on both counts. While Philip relieves himself, Butch goes to a clothes line to steal some civilian clothes for himself. The farmer who owns the car and the home spots him helping himself. While the farmer runs in from his tractor, Butch jumps in the Ford and fiddles with the starter for an interminable time. The farmer nearly catches the two until Philip bites his hand and he releases his grip on the car.
The manhunt team discusses whether locals should shoot if they have a clear shot. Red and Sally say no because of the boy.
Butch learns that Philip's dad is gone. They realize they have some things in common: they are handsome, they like RC, and their dads ain't worth a damn. They are on their own and seek foolish destiny.
Red gets to the scene of the car recovery. They pry open the trunk and find the dead guard, Larry Billings, inside. Sally barfs and Red shows a smidgeon of compassion.
Butch gives Philip an alias, Buzz, so they can go to a store called Friendly's to buy skivvies, britches, rope, and duct tape. Buzz eyes a Casper costume left over from Halloween. A local cop finds the car parked by the store and waits to nab the escapees. The clerk flirts with Butch and gets a nice tip. Butch refuses to buy the Casper costume. Mr. Willits, the store manager, starts to call to report presence of Haynes but Haynes threatens him with a look. Troubles aplenty outside but Butch outmaneuvers them and stops by to pick Buzz up on way out of town. "You ain't so friendly," is Butch's take on the clerks screaming at Buzz for shoplifting the Casper costume. The two are a team.
Buzz and Butch hide behind a barn while the coast clears. Butch forgives Buzz by saying that although stealing is wrong, the Casper costume theft is an exception to the rule. Buzz is embarrassed by his puny pecker (in the words of Terry). Butch looks at it and declares it good sized for a boy his age. Buzz is heartened by Butch's assessment.
Red and Sally believe that Haynes (Butch) and the boy are headed for the Panhandle. Sally outlines Butch's sad life before incarceration. Mom killed herself and Daddy split. After Haynes killed a man who hurt his mom when he was just 8, he stayed clear of the law until he stole a car some years later. Haynes received an inappropriately long sentence. Sally declares that where they are going is not important but why they are going there is very important.
Butch trains his navigator in the ways of map-reading. They pass a trailer and wave just for fun. Turns out it is the team of trained criminologists. The trailer does a U-turn when they spot the Casper costume. A chase ensues. The trailer and truck get separated in the process. The Governor's trailer crashes, much the worse for wear. The Governor tells Buzz's mom that the boy is OK as he smiles for the cameras.
Butch lets Buzz decide what to do, whether to hoof it or stick with the car. Butch informs Buzz that he is headed for Alaska. Buzz considers the options and decides that 1500 miles is too far to walk. Supply inventory is low, just soda, gum, and half a Moon pie.
The Governor wants the trailer back but Red doesn't tell him its condition.
With Buzz now sporting the Casper costume, they go trick or treating even though Buzz is a Jehovah's Witness and Halloween is past. Butch tells him how it's done. They go to a woman's house way out in the country, and she says that he is too late. He missed the popcorn balls. When she sees Butch's gun, however, she changes her mind and gives them whatever she has, including money. They feast on the spoils, mustard sandwiches.
Later, while Buzz sits in the car alone waiting for Butch to check out the road block, the car starts rolling. Buzz finally sorts out the brake from the accelerator and stops it. Then it happens again. A guy out with his family almost hit by the car buys their story about bad brakes and agrees to take them along in their car, enabling the pair on the lam to get through a checkpoint.
The mom in the car with Butch and Buzz blesses her children out and slaps them for spilling a drink in the new car. Butch's face clouds over and he decides to have Bob let them out of the car. Then he kicks the family out with their suitcases and steals their car. The next scene is of the family approaching one of the roadblocks on foot.
Red and Company are getting hungry. They find steaks and tater tots in the trailer and Red starts cooking them up. Bobby Lee tries to put the make on Sally but Red cuts it short to ask Sally how she likes her steaks cooked. Then Red sets the would-be suitor Bobby Lee straight about the mission.
Butch and Buzz talk over the limitations of the Jehovah's Witness religion. Butch introduces Buzz to the fun side of American life by allowing him to ride on the car roof. Later, they stop for dinner and Butch hopes for a side order of nookie from the waitress. Buzz watches out of curiosity. When Buzz is discovered, the couple's mood is dampened. Butch and Buzz get back on the road not fully replenished. They discuss women and love.
Butch and Buzz hide in a corn field to lay low, plan their journey, and catch some sleep. Buzz tells Butch he wants to return home and Butch promises to return him soon. Butch reassures him of his concern for the boy by asking him to make a list of all the stuff he wants to do, such as eat cotton candy, and says he will try to make certain he gets a chance to do some of it.
Sally asks Red whether he was a sheriff when Haynes got his long sentence for stealing the car. Red said Butch's dad was a crook, bad news, and Red thought it would be better for Butch to send him away from the household to an institutional setting. Regret was in his eyes.
A sharecropper, Mack (Wayne Dehart), finds Butch and Buzz in the corn and offers them a place to sleep and Butch agrees. Mack hits his grandson, Cleve (Kevin Jamal Woods), upside the head and Butch does not approve. The two families eat breakfast together the next day and get to know each other. Butch shows Cleve a gymnastic trick like skinning the cat and they practice a little. Butch plays some old 45's and invites Mack's wife, Lottie (Mary Alice), and the boys, to dance. Butch talks about growing up in a whore house watching his mama dance. Mack hears about the manhunt on the radio and the mood changes quickly: Butch threatens him to secure his silence. The farmer's family gets tied up with their mouths taped shut, and Butch is ready to kill Mack for hitting his grandson.
Trust is the topic of conversation and it is clear that Buzz does not trust Butch as much as he did because of Butch's hairpin temper. Buzz shoots Butch in the gut, crying the entire time. Then he throws the gun in the well, throws the car keys on the ground, and runs away. Butch, bleeding profusely, shows mercy and leaves his pocket knife on the table so Mack and his family can use it to free themselves after he leaves. Philip crawls under a fence and runs through a field, leaving a bit of his torn costume on the fence. Butch follows him telling him he's a hero and agrees to let him drive if he will continue on as his running buddy. It is clear, however, that they have reached the end of the line. Philip climbs a tree. Butch is slowly dying from his wound but he continues to follow the boy. Butch asks Philip to go with him to Alaska and he reads the message from his dad on the back of the postcard out loud to Philip. Philip apologizes for shooting him. Butch says he was glad it was Philip who shot him and not some stranger.
Butch and Philip are surrounded by cops. Shotguns abound and Bobby Lee, the FBI agent, gets out a high-powered rifle with a telescopic site and prepares to shoot Butch. Red talks to Butch via a megaphone. Negotiations begin and end with a threat to kill the boy even though the "pistola" is in the well. Gladys, Philip's mom, arrives on a helicopter and she pleads for Philip's life. Philip trick or treats the group of cops and Butch negotiates for Philip's future fun, not his own life. When Philip tries to say that his Mom lets him do a lot of great stuff, Butch is skeptical: "Don't kid a kidder, Philip." Butch makes her promise to allow him to go to fairs and trick or treat and Philip vouches for her veracity as a "real good mama." Butch asks him to walk toward the cops and yell, Trick or treat! The running buddies shake hands goodbye. Philip, still dressed as Casper the Friendly Ghost, starts to go to his mom but returns to Butch who is dying. Philip is worried they will shoot Butch. They hug and begin to walk toward the cops very slowly, hand in hand. Red walks out to talk to them but tells Bobby Lee to keep him "locked down, clean as a whistle." Red drops his gun on the ground and tells Butch to drop his gun. Butch says Pistola is gone, thanks to his partner. Butch tries to hand the postcard to Philip but Bobby Lee, looking through his scope, thinks Butch is reaching for a weapon and shoots him, a mortal wound. Buzz weeps over him. They run and grab the boy as Red looks on and winces.
Red punches Bobby Lee for improper discharge of his weapon. Sally gives Bobby Lee a knee to the groin for good measure. The last scene is Butch in the field again as in the first scene. Only now it is clear that Butch is a ghost too.