The Three Mersquiteers, Tucson Smith (Bob Steele), Stony Brooke (Tom Tyler) and Lullaby Josline (Jimmie Dodd), run into trouble trying to keep Tim Clay (John James), son of their employer Minera Clay (Elizabeth Valentine), out of trouble. They think their problems are over when Tim announces his intentions of marrying Claire Robbins (Lois Collier). But Neil MOrgan (Tom Chatterton), Minerva's lawyer, is plotting to get her ranch through resorting to the water-hole-racket of poisoning her cattle, and puts a squatter on the property, hoping to keep him there until the Squatters' Rights Bill becomes effective.