When Catherine Sumertun was called home from college to the 3,00 acre wheat and sheep Sumertun Ranch along the Washington side of the Columbia River to care for her flu-stricken mother, Sarah, she has no idea what fate has in store. She welcomed the chance to help her mother, but she didn't welcome conflict with Corwin Turnoch, her step-father. She finds romance with the handsome Hank Hirsch when they both toss water in Art Wheeler's face while he smokes in the straw lined lambing pens. The inept Art accidently causes Hank's broken leg. Without Hank the trek over state and federal land with 5,000 sheep is threated. Art is fired and Sarah calls Corwin's bluff about his firing. The strong willed Sarah designated her daughter along with two veteran herders to supervise the annual, financially necessary drive. Catherine welcomes a chance to become a part of the ranch she loves. She survives heartbreak, learns to fly, is dubbed "Boss Lady," curbs a possible cattle-sheep range war, and need the curing waters of Soap Lake for her favorite herder. She humiliates Art again and he promises revenge. Her dire premonition of fire brings many doubts, but save her flock from a horrific fire in the lava walled Grand Coulee. She takes her flocks over the Columbia River atop the Grand Coulee Dam with the reputation as "Shepherdess of the Sumertun Ranch," but she still faces two more life or death challenges.