A 12 episode serial starring Rex, the King of the Wild Horses and Rin-Tin-Tin, Jr. Rex is brought from the island of Sujan, where he is worshiped as a God-Horse, to the U.S. to be trained as a polo pony. He escapes, meets Rinty and with the help of Frank Bradley is returned to Sujan. The natives have been persuaded to turn against their God-Horse, however he is rescued just in time before he is burned as a sacrifice.

Directed by: Ford Beebe & B. Reeves Eason
Written by: B. Reeves Eason & Maurice Geraghty & John Rathmell & Barney A. Sarecky & Ray Trampe
Runtime: 229 minutes
Tagline: Island of Sujan... Infested With Strange Beasts... Place of Lurking Dangers...
Cast:
Rex Rex
Rex, The King of Wild Horses 
Rin-Tin-Tin Jr. Rin-Tin-Tin Jr.
Rinty 
Kane Richmond Kane Richmond
Frank Bradley 
Norma Taylor Norma Taylor
Dorothy Bruce 
Mischa Auer Mischa Auer
Tanaga 
Smiley Burnette Smiley Burnette
Jensen