Josef Vadassy, a Hungarian refugee and language teacher living in France, is enjoying his first break for years in a small hotel on the Riviera. But when he takes his holiday photographs to be developed at a local chemists, he suddenly finds himself mistaken for a Gestapo agent and a charge of espionage is levelled at him. To prove himself innocent to the French police, he must discover which one of his fellow guests at his pension is the real spy. As he desperately tries to uncover the true culprit's identity, Vadassy must risk his job, his safety and everything he holds dear.

Eric Ambler, born 100 years ago next month, mastered as a young man a genre still in its infancy. Joseph Conrad’s “The Secret Agent” (1907) and John Buchan’s “The Thirty-Nine Steps” (1915) preceded his works, and compatriots Graham Greene and W. Somerset Maugham fashioned artful thrillers out of turbulent political times alongside him. But Ambler’s mix of swift pacing, believable protagonists and thrilling locales proved an untold influence on those who took up the spy-story pen in his wake. After all, when James Bond, in the film version of “From Russia With Love,” needed a book to read on a critical train trip, he chose an Eric Ambler novel—specifically, “A Coffin For Dimitrios,” which 70 years after its 1939 publication holds up as a startling, elegant masterpiece of espionage fiction.

Mr. Ambler, a worldly Englishman, is generally credited with having raised the thriller to the level of literature. He brought intellectual substance to the genre at a time when it often suffered from shortages of surprise, maturity, verisimilitude and literary skill. He did that by writing half a dozen eloquent novels that were published, and widely applauded, between 1936 and 1940.