Watch The Forbidden Trail for Free: How to Stream the Movie Online at 123Movies. . When Red Hawk Dugan and his men attack a small wagon train, Colonel Merriwell is killed and the young girl Isobel taken and raised thinking Dugan is her father. Fifteen years later the Colonel's son Jack arrives looking for Dugan whom he learned killed his father. As he hunts for Dugan he meets and falls in love with Isobel only to then learn Dugan is her father.