Ten year old Charlie lost his parents to pneumonia when he was nine and has been living with his Grandpa Will ever since. Grandpa Will has a chuck wagon and hires on to wagon trains to cook for them. Right now, Charlie and Grandpa Will are waiting out on the windy Texas Plains for the wagon train Grandpa Will contracted with to show up. It's been days with no sign of the wagon train. Grandpa Will has ridden out every day to look for the group, leaving Charlie at camp to do chores. To his surprise, a funny looking crooked nosed dog shows up one day. Charlie feeds him scraps and plays with him and soon they become friends. When Grandpa Will finds out, he is not pleased that this odd critter is taking food from their larder. Charlie convinces him that the dog is his friend though. Grandpa Will realizes the boy is lonely and in need of companionship so he grudgingly allows him to stay. One morning as he is leaving, Grandpa Will tells Charlie that he's seen signs of a mountain lion. He warns him to stay close to camp and keep his rifle handy. Charlie tells him that Bolo, whom he has named for the unusual white pattern on his chest that resembles a bolo tie, will protect him. Grandpa tells Charlie not to count on it and once again goes out in search of the lost wagon train.Late in the afternoon, Bolo begins making a noise that is different from any that Charlie has heard him make before. It's a low growl, like a steady rumble. The hair stands up on his back and he looks directly at a stand of trees about thirty feet away from the wagon. Quickly, Charlie grabs his rifle and stares intently at the trees. He is terrified by the sight he sees ... a full grown mountain lion. The lion begins walking slowly towards the wagon and emits a petrifying scream that makes a chill run up his spine. He aims his rifle at the animal but has difficulty controlling the trembling in his hands. Suddenly, Bolo rushes toward the mountain lion and begins barking ferociously at it. Charlie realizes that if he doesn't shoot the animal, his friend will most likely die. He manages to settle his nerves enough to aim but before he can get a shot off, he hears a commotion. He turns and sees his Grandpa Will riding like the wind toward the mountain lion. Grandpa fires several shots at the animal which scares it off. It spins and races off into the brush.Charlie tells Grandpa Will how Bolo ran over to challenge the mountain lion and how he realized that if he didn't shoot the animal, his friend would die. He confesses that he'd been terribly afraid and wonders if he is a coward. Grandpa Will reassures him that being afraid in the face of a threat is a natural feeling and that standing up to the dangerous animal was very brave of him. He comforts Charlie and gives Bolo extra table scraps and a good belly rub. He also tells Charlie that he found the wagon train and they will be there by the next day. They settle down for the night and prepare for the adventures that the next day will bring.