As is true in so many cases, the book, Timeline, is way better than the movie. But that doesn't mean the movie isn't fun though. It is based on the Michael Crichton's novel by the same name. Crichton is responsible for many great books, but is most known for Jurassic Park, which was famously adapted by Spielberg. With this being said you can definitely expect a story with a great premise.
Timeline follows a group of archaeologists who are digging a site at Castleguard, France. They are funded by a technology company, ITC, and have been receiving hints about their site to the point where the boss, Professor Johnston (Billy Connolly), becomes suspicious. He goes to find out what the back story is and the next day his crew discovers a new room at the site which has a note left by the professor from 14th century France.
The professor's son, Chris (Paul Walker), and the crew led by Kate Ericson (Frances O'Connor) and Andre Marek (Gerard Butler) go to ITC to find out what is going on. They learn that the company built a 3d fax machine that tapped into a wormhole sending its packages, or in this case humans, back to 14th century Castleguard, France. The group then heads back in time to go save the professor, who was sent back there to figure out the connection of the wormhole and their site.
While the film has a great premise it probably would have been a lot better if it was made ten years later with a bigger budget. The story starts off strong, but then proceeds to tail off into B-movie territory. It has some performances by actors you will know, but the script doesn't help them, and it certainly doesn't reach the highs of the book. By no means is this a success, but it does well to keep you entertained if you're just looking for a movie that will be a time killer.