Fearing that his recently-acquired step-mother, Ann Dennis, is competing with him for his father's affections, and saddened by the death of his dog, young Danny Mitchell seeks consolation in the companionship of a ferocious, Nazi-trained police dog, Rusty, brought to the U.S. by a returning WWII-veteran. The step-mother, with tender understanding, eventually wins Danny over while Danny pacifies his new dog.

A young Czechoslovak orphan, Loddy Bicek, befriended by an American army sergeant, is brought into the United States as a stowaway by the soldier. He is apprehended, but escapes and makes his way to the sergeant's home town. There, he is befriended by young Danny Mitchell and his dog, Rusty, a K-9 veteran of World War II. A third boy reports Loddy to the authorities, and when Loddy tries to run away, he falls into a deep ravine.

Danny Mitchell, feeling that he has been misunderstood by his parents, takes his dog, Rusty, and leaves home, camping out near the trailer of veterinary Dr. Francis Xavier Ray. Gas escapes in the trailer during the night, and Rusty rescues the vet before he is overcome.

The fourth film in Columbia's "Rusty" series is a lecture against gossiping. A young army veteran comes to town, and Danny and his friends learn that he had spent time in a military stockade for an infraction of a regulation. Danny's friends spread the story all over town. The seriousness of the minor infraction grows with each telling. As a sidebar, Rusty finds a mate and becomes a father.

Faithful dog Rusty helps his master's father win a mayoral race.

Danny Mitchell and his canine pal Rusty befriend blind girl Penny Moffatt. Feeling cheated by life, Penny resists all efforts to cope with her handicap. But with Rusty's help, the girl gains a new lease on life and agrees to adopt a seeing-eye dog.

Rusty, portrayed by a very busy canine thespian named Flame, does exactly what the film's title says he does. But before this prophecy can be fulfilled, the story spends a great deal of time with young Danny Mitchell (Ted Donaldson), who briefly turns to juvenile delinquency when he's denied an expected inheritance

A lost dog tries to find his way back to his beloved master in the final film of the Rusty series.