Dr Benton (Charles Miller) has returned from an expedition to Mongolia where he has apparently found a secret tomb by an ancient Chinese emperor and a scroll that reveals a mysterious secret. Benton is killed by poison during a presentation. Wong and Street begin the investigation assisted by Chinese agent Win Len (Lotus Long). They discover that the secret, now missing, scroll reveals the location of a massive oil deposit...
And it is all rather enjoyable. A neat little mystery with plenty of suspense and misdirection. There is the added fun of the actor who was usually Charlie Chan's bumbling "number one son" leading a detective case!
