Synopsis by Janiss Garza
In 1914 exhibitors weren't yet convinced that feature-length films were marketable, so when Elusive Isabelle by Jacques Futrelle was made into six reels, Universal Studios divided it into two three-reel pictures. This was the first picture; the second was called For the Mastery of the World. Rosa Morini (Belle Adair) and her brother, the prince, are a pair of foreign spies. They are ordered to steal a treaty, which involves both Venezuela and Mexico, from the Venezuelan Ambassador (Fred Truesdale). But the Secret Service finds out about the plot and sends a detective named Grimm (Alec B. Francis) to stop it. The spies infiltrate the Embassy ball and find out the location of the safe. When Rosa shows up later, disguised as a boy, to break into it her brother deserts her and she is captured by Grimm. She confesses everything and agrees to work for the other side. Her brother has kidnapped the Ambassador, and she tricks him into being captured. The prince winds up behind bars and Rosa, with the help of Grimm, aims to go straight.