A letter from Jane, who is nursing British troops, asks Tarzan's help in obtaining a malaria serum extractable from jungle plants. Tarzan and Boy set out across the desert looking for the plants. Along the way they befriend a stranded American lady magician.
| Actor | Role |
|---|---|
 Johnny WeissmüllerTarzan | Tarzan |
 Nancy KellyConnie Bryce | Connie Bryce |
 Johnny SheffieldBoy | Boy |
 Otto KrugerPaul Hendrix | Paul Hendrix |
 Joe SawyerKarl Straeder | Karl Straeder |
 Lloyd CorriganSheik Abdul El Khim | Sheik Abdul El Khim |
 Robert LoweryPrince Selim | Prince Selim |
 Frank PugliaMagistrate | Magistrate |
 Philip Van ZandtKushmet | Kushmet |