Purchasing the Carney Carnival and Road Show, unscrupulous sportsman Martin Trask assumes he has ownership of Rex, the world's greatest trained horse, and its rider, Margie Smith. The girl releases Rex, flees from Trask in a runaway wagon, and finds shelter with young cowboy farmer Jack Merritt, with whom she falls in love.
| Actor | Role |
|---|---|
 RexRex, the World's Greatest Horse (as Rex the Wonder Horse) | Rex, the World's Greatest Horse (as Rex the Wonder Horse) |
 Jack PerrinJack Merritt | Jack Merritt |
 Helen FosterMargie Smith | Margie Smith |
 Tom LondonMartin Trask | Martin Trask |
| SStarlight the HorseStarlight, Jack's Horse | Starlight, Jack's Horse |
 Jim CoreyBit Role (uncredited) | Bit Role (uncredited) |