Jurassic Park may have been Michael Crichton's last novel. Since then, his books have degenerated into action screenplays in paragraph form, each one increasingly disappointing to those who used to look for science as well as excitement in his work. With Timeline, Crichton has exhaustively researched quantum physics and the Middle Ages, digging up enough interesting factoids to form a shiny patina of respectability over what's essentially a shallow, slick fantasy novel full of pasteboard characters chasing each other with swords and causing a variety of ready-for-the-big-screen explosions. Timeline stars a motley band of graduate students who, while excavating a medieval French monastery, find a handwritten distress note from their professor, dated 1357. It seems the tech company that underwrites their research has perfected time travel, except it isn't really time travel; that would be fantasy instead of science. Instead, it's weakly explained quantum-physics-based travel to a different universe in a different time stream, which begs the question of why a note buried in an alternate universe turns up in our own. One way or another, the professor is stuck in 1357, and the students must rescue him. Of course, their knowledge of history turns out to be dangerously wrong, and there's a clock ticking throughout the book to provide tension. This apparently justifies any number of sloppy, glossed-over plot points and one-dimensional characters whose checklists of pre-established skills each come into play like clockwork. Timeline does have the adrenaline-gushing qualities of a good summer thriller, but it also suffers from the accompanying bone-headed illogic. It's the kind of book in which people exchange information they already know in order to inform the reader, and in which a tech intern gets to organize a multi-billion-dollar company's emergency-rescue efforts because no one else has any good ideas. In other words, it's a prefab novelization of a Keanu Reeves movie waiting to happen.