Nancy Brownlee, 10, and her brother Bob, 14, were determined to win the chuck-wagon race for children, held in Calgary, province of Alberta, Canada. But just before the race, they were captured by cattle rustlers. With the help of Colleen, their stalwart collie, the Brownlee children saved the cattle for their father's ranch, the Circle B. And with assistance from the hired man, they built a chuck wagon from an old buck-board. There are exciting episodes preceding the climax, with the cattle rustlers, and a near-drowning, but there is no real question about whether Bob and Nancy will win the race -- it's a foregone conclusion. Appeal is strictly Canadian.