Second that... Non-Stop is one of my all time favourite SF novels. I'm not so sure that learning some of the details would spoil much - in fact the novel was in some edition published with a name that gave a lot away. But I'll avoid it anyway.
"Third" that. I loaned a copy to my wife with a hand drawn (ludicrous) cover that concealed the spoiler of the cover art. Ah, the Golden Age of SF, where the covers could be either completely irrelevant to the content or spoil plot twists... :-)