Mr. Wong, Detective is a 1938 American crime film directed by William Nigh and starring Boris Karloff in his first appearance as Mr.

[1] Simon Dayton is in fear for his life and seeks the help of Mr. Wong to protect him.

Just prior to meeting Mr. Wong, Dayton is found dead in his office in San Francisco without a mark on him.

Several witnesses testify Dayton was alone in his office that was locked from the inside.

Though the police view Dayton's death as due to a heart attack, Mr. Wong discovers a broken glass ball that contained poison gas.