It's just after the Civil War in Texas and Sam White has found a rich deposit of bauxite. But lawlessness abounds and Jim Tulane and his henchmen are in control. Tulane knows White has found something but is unable to find out what and kills him. He also knows the key is in a toy wagon White gave to his son. The son figures out the puzzle only to learn that Tulane's henchman has already accidently found the answer.

When Sam White returns to his Panhandle Ranch after the Civil War, he is run off his own property by Jim Tulane, the man he entrusted to keep it running. Tulane has hired a gang headed by Mark Brannigan to help him take over the area, and they have managed to subdue the lawmen in the area, including Sam's father, Sheriff Tom "Gramps" White. Sam asks for help from the Texas governor, but is told that the state's resources have been depleted by the war and the many outlaw gangs taking advantage of the chaotic times. Sam plans to assist with the recovery of the area by mining bauxite found on his property and has negotiated a deal with an aluminum company. He intends to share his resources with the other ranchers, but must first wrestle control from the outlaw gang. Sam buys guns and ammunition from St. Louis to fight the gang, but needing assistance to smuggle the supplies into the area, sends his father a hidden message in a birthday gift basket, which his young son Red delivers by stagecoach. During the stagecoach ride, Red sits in front with the driver and talks about all the things his father taught him, including the Morse code, until he is interrupted by Tulane's men, who hold up and search the stage. The outlaws discover the hidden message, but say nothing and allow the stage to continue. When Red arrives at the ranch, his friend, Judy Dawson, is waiting for him. Gramps opens his present and is bewildered to find a bottle of champagne, as he does not drink, but appreciates the box of cigars and the message, which reveals when Sam will be secretly arriving and the route he is taking. Several ranchers come to the ranch to tell Gramps they are being forced out, but Ted Gately, a writer from Parker Weekly who has just shown up to do a series of articles about the region, convinces them to stay. Ted's presence pleases Judy's sister Betty, who helps Gramps around the house, and Ted also tries to help by going with Gramps to meet Sam at the appointed time. However, the outlaws reach Sam first and take him to Tulane's office, where they torture him to learn his plans to boost the area's economy, so that they can profit from it. Instead of talking, Sam becomes amnesiac from the trauma, but Gramps and Ted rescue him from the outlaws after a gunfight. Soon after, Sam focuses on a miniature wagon, which is a present for Red, and though confused, believes the wagon contains an important message. After the outlaws learn from the doctor that Sam's memory might return with a second shock, Tulane abducts Red and Judy and goes to the White ranch to tell Sam he will kill the children. Unaware that they have managed to escape, Tulane kills Sam in a fight. Later, the grieving Red is studying the wagon that his father gave him, and remembers that Sam taught him the Morse code. In a seam of the wagon's cover, Ted and Red find a series of dots and dashes, which spell out the words "look in bottle." Inside the bottle is a note saying that ammunition is coming by wagon that day, so Gramps rounds up the ranchers. Before Brannigan, who overhears about the ammunition, can alert the other outlaws, Ted manages to intercept the delivery and directs most of the drivers to Castle Rock, where Gramps and the ranchers will meet them. However, acting as a decoy, Ted takes one wagon on the original route, unaware that Red has followed and jumped into the back. The outlaws chase Ted and take him to their hideout at a mine, and are about to kill him, when Red sneaks in and knocks out Ted's guard. As Red and Ted escape the mine, a fire erupts inside. Meanwhile, the sheriff arrives with the ranchers, and a shootout ensues. Looking for cover, the outlaws go into the mine, and are killed when the fire reaches the ammunition brought in from Ted's wagon. Later, after order is restored, Ted says that he will stay in the area while he writes the rest of his articles, and everyone, especially Betty, is pleased.