Night over Water — Ken Follett

In 1939, with war just declared, a group of privileged people board the most luxurious airliner ever built the Pan American Clipper, bound for New York: an English aristocrat, a German scientist, a murderer under escort, a young wife escaping her husband and a charming, unscrupulous thief. For thirty hours, there is no escape from the flying palace. Over the Atlantic, tension mounts and finally explodes in a dramatic and dangerous climax.