Starman Jones — Robert A. Heinlein

WHERE WERE THEY? IN FACT, WHEN WERE THEY? AND HOW COULD THEY GET BACK?

It's easy to stow away on an intergalactic spaceship, if you're a smart lad like Max Jones. But it's quite another thing when the spaceship touches down on an unknown planet after passage through a time warp...perhaps an unknown century. Especially when the spaceship's pilot dies, and his charts and are destroyed. Now survival was up to Max...