Timeline
Michael Crichton
 In the middle of the New Mexico desert, a vacationing couple comes across an ill man wandering miles from town. They find the man, Joe Traub, is a physicist and an employee of a company called ITC. However, ITC's headquarters are mysteriously far from where Traub was found. Traub soon dies of a cardiac arrest. The hospital receives an MRI scan later, which reveals that Traub's blood veins did not match up to each other. Traub, being the last of his family, is taken and cremated by ITC to prevent any further evidence about his death from coming through to the public. In the Dordogne region of France, Professor Edward Johnston leads a team of historians and archaeologists studying the remains of the medieval towns of Castelgard and La Roque. Suspicious of the detailed knowledge of the site shown by ITC (their funder), Johnston flies to ITC's headquarters in New Mexico to investigate. While he is gone, the archeologists make a startling discovery in the ruins; a lens from a pair of glasses as well as parchment with a request for help written in modern English, apparently in Professor Johnston's handwriting. Researchers Chris Hughes, Kate Erickson, André Marek and David Stern fly to ITC and meet Robert Doniger, its founder, who tells them Johnston has used their quantum technology to travel to Dordogne in the year 1357, but has not returned as expected. Chris, Kate, and Marek agree to travel back themselves to find him. Stern remains behind, distrusting ITC's technology and believing they aren't telling them everything. They dress in period specific clothing, but Doniger allows only biodegradable modern advances to go back, banning plastic and weapons. When they arrive in the past, the team is plagued by misfortune. They are attacked by a group of horsemen led by Sir Guy, who kills the ITC military escorts and causing a grenade snuck on the mission to go to the present, destroying the transit pad. Unable to return, Kate and Marek are taken away by the men of Lord Oliver of Castelgard. Separated from the others, Chris accidentally declares himself as a noble to a boy who helps him and is led to Castelgard. The boy is revealed to be the Lady Claire in disguise, trying to escape from the leader of the horsemen, Sir Guy de Malegant. In the castle, Chris and André Marek find themselves challenged to a joust by Sir Guy and his second, Sir Charles de Gaune. Chris, instructed by Marek, lies on the ground after Sir guy hits him on the chest on his second run. While Marek fought with Sir Charles de Gaune, Sir Guy tried to kill Chris. However, André fights with Sir Guy and manages to beat him. Lord Oliver orders the death of André and Chris, but Kate helps them escape Castelgard and they are pursued by Guy and his knight Sir Robert de Kere. Lord Oliver believes that Johnston knows a secret passageway into the otherwise impenetrable castle of La Roque. Oliver's enemy Arnaut de Cervole, otherwise known as the Archpriest, is approaching the Dordogne to lay siege and Oliver wants the secret to defend La Roque. Johnston helps Oliver develop a weapon despite knowing that historically Oliver loses the siege, while Chris, André, and Kate use clues from the future to search for the passage themselves. Chris realizes that someone else is in the past with them and spying on their transmissions. Eventually Robert de Kere reveals that he is Rob Deckard, an ITC employee and former marine driven insane from the accumulation of "transcription errors," deformities that build up over multiple quantum trips. De Kere intends to take their trip home for himself. Meanwhile at ITC, Stern and the vice president, Gordon, try desperately to repair the transit pads. It is revealed that Doniger is trying to use the past as a marketing tool. After Lady Claire helps Kate, Chris, and André elude Arnaut's men, André enters La Roque as Johnston's assistant while Chris and Kate discover the passage. As Arnaut begins his siege, Oliver decides that Johnston is hiding information and takes him to a torture device known as Milady's Bath to drown him. Kate fights and kills Guy on the rafters of the Great Hall, while André and Chris are able to rescue Johnston when Arnaut himself intervenes and defeats Oliver in a duel. Arnaut thanks them and leaves Oliver to die. As the battle rages, de Kere attacks Chris to get his ceramic marker, but Chris manages to set him on fire with Johnston's automatic fire and spittle. ITC and Stern finally repair the landing area just in time for the travelers to return. André—who realizes he has longed for this life—decides to remain in the past with Lady Claire while Chris, Kate, and Johnston return to 1999. When it becomes clear that Doniger had little regard for the lives of the travelers, the researchers and engineers, mainly John Gordon, send him to 1348—the outbreak of the Black Death. In the epilogue, Chris and Kate are expecting a child together. The researchers find André and Lady Claire's graves and discover that André lived out a good and satisfying life. His gravestone reads a message in French to his companions, quoted from Richard Lionheart, - "Companions who I love, and still do love,... tell them my song."