The Amalgamated Smelting Company, supported by the U.S. Government, have brought suit to recover $5,000,000 damages for loss of lands confiscated by Rebels in a foreign country and the U.S. President appoints Frederick Thurston as envoy to the Arbitration Commission, who will meet at Bar Harbor to adjust the claim. The Imperial Smelters Company, the opposite side, are represented by Henri Sutro, who immediately cables to his government for the assistance of a secret service detective. Jean Thiers, a famous army spy, assisted by Madame LaRoche, are rushed to America to join Sutro. Thurston secures the aid of Jack Maher and Mary Joyce, secret service agents of America. It is then a battle of wits between the American contingent and the foreigners. Sutro and his aids meet Thurston, but accomplish nothing and set to work to secure the American documents by means fair or foul. At Washington and Bar Harbor, Thurston is watched by the foreign agents and on the other side Maher and Miss Joyce are devoting all attention to the movements of Sutro and his spies. On arrival at the Bar Harbor hotel, Thurston consigns his portfolio to the clerk, who places it in the safe. They temporarily secure an old mansion and there install Madame LaRoche. The game is on and Thiers, by adroit methods, succeeds in stealing the American State documents from the hotel safe. Madame LaRoche, preparing to leave the hotel, is coming downstairs. At the last step she trips and falls into the arms of Thurston, who is standing at the bottom; she has slightly sprained her ankle. Thurston assists her to his auto and drives her to the estate, thus an acquaintance is formed and Madame LaRoche being attracted by the envoy's charming manner, invites him to call upon her at the mansion. Another interview and Thurston and Madame LaRoche are in love. By observation, Thiers becomes suspicious of his companion and madly jealous. Having the papers, he then proposes to Lille LaRoche that they return to Brussels, but she refuses and a quarrel ensues, which ends in Thiers begging for her pardon. He then wires to Sutro at Washington that he has secured the papers, but Maher intercepts the messenger boy, states that the message is for him and discovers the robbery. Thiers has hidden the State papers in an old vault; he then meets Thurston and asks him if he, Thurston, has not lost some important documents, and proposes to assist him in recovering same. Thurston follows Thiers to the vault and seeing his portfolio, rushes to seize it. Theirs escapes through the door and locks Thurston in. Next morning Thiers goes to the window of the vault to gloat over his prisoner. Joyce sees him and there is a struggle, Joyce being overpowered. Theirs then turns on a faucet of water which will flood the vault. The water gradually rises up to the envoy's waist and finally to his face. He is about to give up when he is rescued by Lilie, Maher and Joyce, Lilie having shot the arch-fiend, Thiers. His clothes saturated with water, Thurston rushes to the arbitration room and delivering his papers, carries the day. Lilie is released by order of the President and wins a noble husband.