Dr. Harry Trevor (Bryant Washburn), Dr. Frank Bracken (Walter Miller) and Dr. Charles Phillips (Fred MacKaye) are sent by the Caranfellow Institure to Africa to search for a formula that will cure infantile paralysis. Trevor is accompanied by his wife, Georgia (Viva Tattersall), and their young son Jan (Dickie Jones). Trevor discovers the formula but Bracken and Phillips conspire to steal it. Trevor writes half the formula on a piece of parchment and the other half on a flexible metal band which he places on Jan's wrist. Jan and his chimpanzee playmate wander into a menagerie on the post and his mother loses her life protecting him against a lion. Trevor is knocked unconscious, and the chimpanzee leads Jan into the jungle. Bracken and Phillips, believing Trevor is dead, head back to the U.S.A. They return fifteen years later, find the parchment half of the formula and lead a safari on a search for a boy named Jan who has been raised by the jungle animals.