Elusive Isabel is a novel by Jacques Futrelle first published in 1909. Set in Washington, D.C., it is a spy novel about an international conspiracy of the ‘Latin’ countries against the English-speaking world with the aim to take over world control. The eponymous heroine, Isabel Thorne, is a young woman, half British, half Italian, who works for the Italian Secret Service. She has been commissioned to bring about the signing of a secret contract, in the capital of the enemy, by representatives of all countries involved, both European and American. Her brother, an inventor, has devised a secret weapon by which missiles can be fired from submarines  which will, it is hoped, secure military domination over the rest of the world…