A hopelessly hopeful drifter, a bitter young woman, and a helpless child live on the docks, spending their days in poverty and listless wandering. Overhead, a dredge hauls up mud and trash from the nearby seabed — the same mud and trash from the day before. They finally decide to leave for the city to seek fulfillment, only to encounter further privation, destitution, temptation.

Inventor Peter Marchmont has discovered a purple light that renders the user invisible. On his release from prison, Marchmont, disguised as Victor Cromport, uses the light to revenge himself against his former wife, Jewel, and her partner, James Dawson, who framed him for theft. Making himself invisible, Marchmont gradually ruins Dawson. He so wins Jewel's confidence and love that she is willing to kill Dawson at Marchmont's request. Finally, Marchmont leaves the scheming couple to their own misery and marries Jewel's sister, Ruth Marsh.

A wealthy family is blackmailed. Murder results. And a nurse at the scene of the crime is determined to figure out who-done-it.

Nightclub entertainer Ruby Carter moves from St. Louis to New Orleans to escape Tiger Kid. At Ace Lamont's club, she gains fame but faces drama with Ace's ex Molly. A jewel theft and fixed fight lead to confrontations.

A kingdom's ascending heir, marked for assassination, switches identities with a lookalike, who takes his place at the coronation. When the real king is kidnapped, his followers try to find him, while the stand-in falls in love with the king's intended bride, the beautiful Princess Flavia.