Just back from Shanghai, Ralph Bonner (Frank Mayo) and his brother Jim (Rex Lease) deliver a priceless dagger to their boss, Lee Fong (Edmund Breese), but the weapon is promptly seized in a deadly clash with Chinatown's ruthless Madame Ying Su (Carmel Myers), and the crime is pinned on Jim. Discontent with the cops' progress on the case, Jim decides he'll solve the case himself, with the help of Fong's lovely ward Lotus (Barbara Kent).