In northern Arizona near Corazón Canyon, a married couple driving through the desert encounter an elderly man.

In the Dordogne region of southwest France, Professor Edward Johnston leads a group of archaeologists and historians as they study a site that includes the fourteenth-century towns of Castelgard and La Roque.

Suspicious of the detailed knowledge of the site shown by their funds provider ITC, Johnston travels to New Mexico to investigate.

Four of the researchers—graduate students Chris Hughes and Kate Erickson, assistant professor André Marek, and technology specialist David Stern—are flown to ITC's research headquarters in Black Rock, New Mexico.

During the flight, ITC vice president John Gordon informs them that Johnston traveled to the year 1357 using their undisclosed quantum technology.

The ITC guards are killed, and one activates a grenade before being fatally wounded and initiates his return, causing the present-day transit pad to be damaged by the explosion.

Kate and Marek find Johnston at a monastery, but he is soon taken captive by the soldiers of Lord Oliver de Vannes, an English knight and resident lord of Castelgard, who thinks that Johnston knows the secret passageway to the otherwise impregnable castle of La Roque, which Oliver controls.

After escaping Arnaut's forces, Chris and Kate find the entrance to the passage at a decrepit chapel while Marek gains entry into La Roque by posing as Johnston's assistant.

The person is revealed to be de Kere, who is really Rob Deckard, an ITC employee driven insane from errors in the process of teleporting to another time that built up in his body over multiple trips, much like the elderly man the couple in Arizona found.

Marek, who always wanted to live in the Middle Ages, decides to stay behind, while Chris, Kate, and Johnston return to the present.

The historians and Gordon confront ITC president Robert Doniger, who had little concern for the travelers' safety and intends to exploit the quantum technology for corporate gain.

He fights multiple soldiers, not hesitating to take their lives; bravely stands up to medieval warlords and Archpriests; and is very convincing in the role of a knight.

When Professor Johnston, Kate, and Chris return to their own world, they find Marek's grave and discover that he lived a happy life in that alternate universe.

Kate Erickson began her college career as an architecture student but found it boring and switched her major to history.

Kate now works the Dordogne site from the perspective of architecture, examining the ruins to see how they were built and to make recommendations for restoration.

David Stern is a physicist who takes a job with the Dordogne River Valley archeological site just to be close to where his girlfriend is attending school.

Crichton's narrative seems to support Cantor's notion that the work of academic medievalists amounts to little more than subjective reinventions of the medieval era.

The adaptation was written by Jeff Maguire and George Nolfi, and directed by Richard Donner, and stars Paul Walker as Chris, Gerard Butler as Marek, Billy Connolly as Professor Johnston, and Frances O'Connor as Kate.