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.

Roscoe flirts with a girl in the park. Later he takes his wife and mother-in-law to the movies only to see his flirtation showing on the screen.

Arbuckle escapes the watch of his domineering wife and heads for Coney Island. Keaton arrives that same day with his attractive, and rather easy, girlfriend, who is immediately stolen from him by St. John.