Black Lightning (1924)

Accompanied by Thunder, the dog who rescued him from the firing line in France, World War veteran Ray Chambers goes to the mountains to recover from his war injuries. There he meets Martha Larned, a lonely mountain girl who lives with her little brother, Dick. Ray discovers that Martha is the sister of his dead buddy, Frank Larned, and he decides to stay and protect her from harassment by Jim Howard and his half-witted brother, Ez. When Dick is hurt in a fall, Ray goes for a doctor; Ez kills Jim and attacks Martha; and Thunder takes care of Ez. Ray and Martha then get married.