“Timeline” sells itself as “A Connecticut Yankee in King Arthur’s Court: The True Story.”

A staple of time-travel stories is to send someone back to the Middle Ages, with knights in armor, jousting, ladies in waiting and all that cool stuff. The formula was used most recently in the terrible Martin Lawrence comedy “Black Knight.”

“Timeline,” based on a Michael Crichton novel, takes this device and attempts to make it historically and pseudo-scientifically accurate.

The explanation for time travel differs from Crichton’s book. In the movie a FedEx-like corporation tries to invent a machine that will transport matter from one city to another “like a fax machine.” The scientists instead discover a wormhole that is a conduit to a village in 14th century France. In other words, while trying to invent one “Star Trek” device, they stumble across another.

Archeologist Edward Johnson (Scottish comedian Billy Connolly) leads a dig at the village, not sure why his corporate backer, Robert Doniger (David Thewlis wearing a Bill Gates Halloween costume), is so interested in the village. Johnson’s son, Chris (Paul Walker), shows up, hoping to score with pretty grad student Kate (Frances O’Connor). He doesn’t score, but he still hears a lot of exposition about the village and a crucial battle the French and English fought there 600 years ago.

The professor leaves to meet with his multibillionaire sponsor. Two days later the archeologists find an SOS from Professor Johnson – rolled in a parchment that hasn’t been touched since 1357. Chris realizes that, somehow, his father has become the subject of his own archeological dig.

As plot hooks go, this is a corker.

Chris, Kate and three other students, Marek (Gerard Butler), Stern (Ethan Embry) and François (Rossif Sutherland), fly to Doniger’s research center in New Mexico demanding answers. He explains the whole wormhole thing to them, then sends most of them back in time to save Chris’ father.

Meanwhile, back in the 14th century, the time travelers arrive in the village and realize the major battle they were researching will occur in a few days. But Marek, ignoring the rules stressed in every time travel movie, interferes with the past when he rescues a damsel (Anna Friel) from an English prison.

She turns out to be the princess that the French army fought the battle for, so Marek may have stopped the fight before it begins. Obviously he didn’t see that episode of “Star Trek” where Dr. McCoy saved Joan Collins and caused Hitler to win World War II, or he would have known better.

Time travel movies work best when the filmmakers don’t bother explaining how time travel works and focus instead on characters trapped in a different world. Director Richard Donner, responsible for a host of well-crafted popcorn movies going back to “The Omen,” understands this and plunges into the adventure as soon as he can.

The action is amazing. Rather than rely on computer-generated special effects, as any other director would do today, Donner stages battles using actual catapults and flaming arrows aimed at a life-size castle production designer Dan Dorrance built in the Montreal countryside.

Not only does this create spectacular views as thousands of soldiers storm the castle, it also allows for such precious dialogue as, “There are a goodly number of trebuchets on the field, my lord.”

“Timeline” is first movie to realistically depict the rank living conditions of the Dark Ages since “Monty Python and the Holy Grail,” a film it unintentionally resembles here and there (I expected to hear Terry Jones say, “There’s some lovely filth over here, Dennis”).

“Timeline” rolls through its plot quickly and allows the audience to savor the good parts. It’s slick entertainment that does its job, even if no one will remember it six years from now, much less six centuries.