Below the Line on AllMovie

This melodrama required less stunts than usual from dog star Rin-Tin-Tin and more "acting." Always the trouper, Rin-Tin-Tin proved to be the histrionic equal of his co-stars. Slasher (Rin-Tin-Tin, a famed fighting dog, falls off the train that is carrying him. He is found, broken in spirit, by Donald Cass (John Harron). The dog is regenerated by Donald's love. Donald is equally devoted to his sweetheart, May Barton (June Marlowe), a minister's daughter. A wealthy young woman donates a large sum of money to the church and is later found murdered. The sinister Jamber Niles (Pat Hartigan) knows that the money is in Donald's safekeeping, and he attacks the young man. Slasher springs into action and kills his master's assailant. Jamber's half-wit brother Cuckoo (Victor Potel) sets a pack of bloodhounds on Donald and May, but once again Slasher comes to the rescue and fends them off. Evidence proves that Jamber was the woman's murderer. Donald, May, and the loyal Slasher look forward to a happy life together.