The Secret Visitors

Dr. Lockhart encounters an old man in Paris, one of thirty-odd 'dying grandfathers' who commit suicide rather than answer the simplest questions about themselves or their origins. Lockhart has been retained by the World Security Organization to find some connection between these men and the threat of nuclear war hanging over the world. Before dying, this broken down old boulevardier 'converses' with him in a language not available on the Berlitz syllabus. Then things go galactic. The Interstellar Tourist Agency is organizing package holidays to terrible, decadent Terra as part of its fell scheme against the Galactic Federation. A bit like the 1956 film version of Raymond F. Jones 1952 fix-up novel, This Island Earth -- only different.