Russian brothers Count Boris and Alexis Rabourdin obtain a Japanese coastline defense map and plan to sell it to German agents in London. In America, Alexis schemes to marry wealthy Eve Bertram, who loves him. Boris, meanwhile, falls in love with Christine Lesley, Eve's neighbor whom Eve's brother Guy, an amateur inventor experimenting with explosives, also loves. Nogi, a Japanese spy sent to obtain the explosives, who serves as Guy's valet, plots to destroy the map. As Boris prepares to leave for London, he gives Christine an old Russian coin as a keepsake. To show Guy that she does not care for Boris, Christine attaches the coin to Guy's watch chain. That night Christine discovers Alexis' dead body. Grief stricken, Eve summons Detective Williams, who finds the coin near the body. Guy, who fought with Alexis, thinks that he killed him. After Christine agrees to marry Boris for his silence, Guy considers suicide, but during a fight, Nogi sets off an explosion killing Boris. Badly injured, Nogi confesses killing Alexis and dies as he sees Christine destroy the map.