The directors of the company operating the Hope Mine suspect a leakage in ore and send young Gause to investigate. Arriving on the scene, Gause and Merry, the pretty stenographer at the office, become friends. In looking over the property Gause determines to explore an old shaft. A week later Gause learns that ore is being shipped away at night, but while he is securing evidence the investigator is overpowered in the dark shaft and left unconscious. In an endeavor to imprison Gause, the mine foreman explodes a section of the mine, causing a cave-in. Merry, in the meantime, has suspected that all is not well with her sweetheart and organizes a rescue party. Gause is liberated, the dishonest superintendent is exposed and the mystery of the Hope Mine is cleared up.
—Moving Picture World synopsis