The Chinese Secret Service sends an undercover agent to investigate reports of an island ruled by a Chinese criminal named The Cobra who holds the residents in virtual slavery while running his illegal narcotics and white-slavery empire.

On her debut as an opera star, Marion Stuart is interrogated and possibly implicated in the death of a male acquaintance. Released, although thoroughly shaken-up, Marion attempts to perform but loses her voice onstage. Humiliated, but driven to sing, she travels to South America under the assumed name of Maria Delasano, and works in an opera company under the tutelage of Feodor Glinka, who wants her to shun men and save herself for her art. Mary resists the persistent attentions of wealthy young Phil Roberts, who follows the company in hopes of marrying her. ...

Mary is called the "Midnight Flower" because each evening at midnight she does a wild dance atop a gaming table in a local gambling den. A young Spaniard in love with Mary, who would rescue her, stages a holdup at the most profitable table and passes the money on to her. In attempting to escape, she is caught, arrested, and jailed. While she is in prison, she meets a young evangelist who runs a mission in the slums. They fall in love, and on her release Mary joins him in the missionary work. This sets the local tongues wagging and complicates the affair until it is revealed that Mary is the daughter of a wealthy family--lost to a kidnapper when she was an infant.

Herbert Pomeroy's wife Juanita spends his money extravagantly and irresponsibly, finally driving him to bankruptcy. Desperate, he sends his son Frankie to live with his friend Henderson, a South Seas trader, then commits suicide. Although Juanita spends years searching for her son, she finally gives up and takes a world cruise on the yacht of wealthy Jules Lennox. One day the yacht docks on Henderson's island and Juanita, meeting Henderson, persuades him to let her be Frankie's governess. Complications ensue, involving a poor physician, a jealous island woman and a witch doctor.