Background to Danger — Eric Ambler

Kenton's career as a journalist depended on his facility with languages, his knowledge of European politics, and his quick judgment. Where his judgment sometimes failed him was in his personal life. When he finds himself on a train bound for Austria with insufficient funds after a bad night of gambling, he jumps at the chance to earn a fee to help a refugee smuggle securities across the border. He soon discovers that the documents he holds have a more than monetary value, and that European politics has more twists and turns than the most convoluted newspaper account.