This book takes readers on a picnic with Arty and his friends Esther, Jasper, and Tom. When they ride to an unfamiliar section of the Circle A, they discover a beautiful little valley. A violent storm interrupts the picnic and sends the four friends riding for cover. By the time they reach an old line shack, the storm is raging; and Tom has disappeared. Arty rides back into the storm to rescue his friend, but both of them face serious danger.