Andy Marvin, soon after his arrival in Wyoming, buys a sorrel pony from a man who is abusing it. Although Andy is bucked off, run away with, and subjected to all the mischievous tricks a Western pony can think of, he gradually tames tough little Sunny. Eventually they become inseparable companions.

With Uncle Wes, the head game warden, and Sally, "a top hand on any ranch" Andy and Sunny share in a series of dangerous adventures which include a search for game rustlers.

This is a novel of rip-roaring action by a man who knows his locale and has an exciting story to tell.