A boy named Mark, tired of being sick with cancer, conceives a plan to climb Mount Rainier, and runs away from home with his dog, Beau--but with over two hundred miles between him and his goal, and only anger at his situation to drive him on nothing will be easy, and only his best friend, Jessie, suspects where he is heading.

Told in alternating chapters, 12-year-old, terminally ill Mark conceives a plan to climb Mt. Rainier and runs away from home with his dog while his best friend Jessie wonders if she should betray Mark's trust. The plot contains mild violence.