Two competing teams of scientists search the African jungles for a secret formula.
Noah Beery Jr.
Jan Trevor
Dorothy Short
Mona Andrews
Harry Woods
Borno
Bryant Washburn
Dr. Harry Trevor
Walter Miller
Dr. Frank Bracken
John Davidson
Prince Samu
Fred MacKaye
Dr. Charles Phillips
Viva Tattersall
Georgia Trevor
William Desmond
Allen
Grace Cunard
Mrs. Camerford Amster
Russ Powell
Henry Andrews
Don Brodie
Dr. Carl Neff
Harry Worth
Dickie Jones
Jan Trevor as a Boy
Eddie Kane
Gen. Tichak
Stanley Andrews
Emperor Mena
Richard Alexander
Navigator (archive footage)
King Baggot
Dr. Pierce
J. Frank Glendon
Speaker at Conference
Al Ferguson
Guard of Mu
Eric Mayne
Doctor at Conference
J.P. McGowan
Freighter Captain
Charles Murphy
Grubb, Freighter's Mate
Eddie Parker
Emperor's Guard / Mu Sentry
Buddy Roosevelt
Batu
Hal Taliaferro
Lancer Officer-in-Charge
Gwendolyn Logan
Mrs. Henry Andrews
H. Burroughs
Kutu
