John Burkett Ryder, "the richest man in the world," determines to discredit a judicial decision which works against the interest of his millions by discrediting its author, Judge Rossmore, and causes impeachment charges to be laid against him in Congress. The judge's daughter Shirley Rossmore, learns of his trouble and returns home from Paris, where she has won success as a writer. She is loved by Jefferson Ryder, son of the magnate who is slowly killing her father. Determined to force the millionaire's hand, she publishes "The American Octopus" under a pseudonym, using Burkett's character as the central figure. He is attracted by the book and brings Shirley, whom he knows as Sarah Green, to his home to write his biography. This is the opportunity she is seeking, as it gives her a chance to obtain the two letters which will clear her father's name. Jefferson Ryder helps her secure the desired papers, but his father catches him and denounces him as a thief. Shirley, who loves Jefferson, cannot stand to see him so branded and confesses her identity to his father. The "Lion" had long since been won by the charm of the "Mouse," and the story is cleared up in pleasing style. - Moving Picture World 1919.