The latest assignment for respected detective Charlie Chan has come directly from the government and involves the disappearance of a scientist named Harper, who was working on an extremely important serum. When the scientist is killed, Chan must sort through all very likely suspects, including the man's sister and his butler.
| Actor | Role |
|---|---|
 Sidney TolerCharlie Chan | Charlie Chan |
 Mantan MorelandBirmingham Brown | Birmingham Brown |
 Edwin LukeEddie Chan | Eddie Chan |
 Hardie AlbrightWalter Meeker | Walter Meeker |
 Janet WarrenJean Kent | Jean Kent |
 Al BridgeSheriff Mack | Sheriff Mack |
 Edith EvansonLouise Harper | Louise Harper |
 Dorothy GrangerStella Graham | Stella Graham |
 Cyril DelevantiRoth | Roth |
 Jack IngramLloyd Archer | Lloyd Archer |
 Lester DorrMichael Strong | Michael Strong |
 Frank ReicherHarper | Harper |
 Henry HallInspector Godfrey | Inspector Godfrey |
| JJoe WhiteheadDr. Samuel R. Peabody | Dr. Samuel R. Peabody |
| DDanny DesmondBellboy | Bellboy |
 Ralph LewisOfficer Jim Kimball | Officer Jim Kimball |
| JJohn BreenPolice Officer (uncredited) | Police Officer (uncredited) |