The first of three inexpensive serials produced by Louis Weiss for Poverty Row company Stage and Screen Productions, The Black Coin centered around 12 black coins, who together form a treasure map. The plot was as old as the Hollywood Hills, and didn't quite deliver the same punch by 1936, despite the addition of the popular G-men to the proceedings. Secret Service agents Ralph Graves and Ruth Mix go in search of the villains who are using the Caswell Shipping Company as a front to their smuggling operation when they stumble over the secret of The Black Coin. Ruth Mix, the daughter of Tom, furnished much-needed name value to all three Stage and Screen serials. William Desmond, a major serial star in the silent era, plays a bit as a bartender in The Black Coin, while, more amusingly, veteran stunt man Yakima Canutt appears as a character named "Ed McMahon."