The Mystery of the Riverboat

Jean Duval [Ch. 5]

Louis Schaber

Dr. Hartman [Ch. 1]

Hermann Einreich [Chs. 1-2]

Jug Jenks [Chs. 1-4, 7]

Rudolph Toller

Charles Langtry

Batiste

Sawyer, the garage owner [Chs. 5, 10]

Bruno Bloch