Lieutenant Commander John Byrne of the Naval Secret Service and his partner Pvt. Bill Riggers chase criminal Dr. Sin Fang, who is desperate to find a lost sacred seal. (The fifth and only surviving episode of a six-part serial about an evil mastermind inspired on Sax Rohmer's Dr. Fu Manchu.)
H. Agar Lyons
as Dr. Sin Fang
Fred Paul
as Lt. Comdr. John Byrne R. N. of the N. S. S.
Wally Patch
as Private Bill Riggers
Fred Rains
as Professor Harbray
Evelyn Arden
as Betty Harbray
