Frank Donald, a young Englishman, who spent his summers at his western ranch, was fond of taking long rides through the woods on his favorite mare, a beautiful grey. On one of these occasions, he left the grey by the roadside, whilst he made his way through the thickets to the brook to drink. Pedro, a half-breed, was eagerly waiting this opportunity, and when Frank stooped to drink, make away with the mare. Several months elapsed when Dolan, a respected ranch owner, visited a camp of horse dealers and purchased a beautiful grey mare, with which he surprised his daughter, Doris. She tried out the mare, and upon returning, tied it in the front yard, while she sought her father, to express satisfaction, and thank him for the beautiful present. The ever-alert Pedro, now saw his chance to divert suspicion. Knowing that Donald followed close behind, with some cowboys, he slipped a branding iron on the grey's saddle as it stood in Dolan's, and rode hastily away on his own horse. Dolan noted Pedro's strange actions and gave chase. Meanwhile, Donald and the boys discovered the grey and the tell-tale iron at Dolan's. Doris innocently told them in which direction her father had gone, and they immediately followed. Donald, however, remained to claim the mare, much to Doris's surprise. Upon learning the truth from her, he realized with horror that a horse thief's fate was about to befall an innocent man. Directing her to ride the grey, he mounted his own horse, and together they rode madly to stay a hastily-formed sentence. The rope was already about Dolan's neck when Doris and Frank came into sight. The grey stopped short, Doris took steady aim, the rope cracked, and Dolan fell to safety. Pedro, the real culprit, was then sought, while Frank remained to receive the father's thanks and the daughter's admiration.