** spoiler alert ** This is pure fantasy or airport fiction, but Crichton does add his science references (about wave properties of light, which makes a reader explore the possibilities of alternate dimensions). It details how a group of historians and archaeologists end up in the Middle Ages and how horrible this age is; people are randomly beheaded if they're in the way, as the historians' arrival shows, and modern man - and his puny physique - stands little chance. It's about survival of the fittest, alternate dimensions, and other weird things associated with quantum mechanics - a perfect literary escape read. If you're a physics/science buff, don't read the footnotes or you'll be obsessing about light particles, alternate dimensions, and quantum physics.