Timeline starts out as a story of science, but ends in fantasy. What else would you expect from a time-travel novel?
ITC--a company located in the New Mexico--is hard at work developing quantum technology. Secretly, they have found a way to transport humans back in time. The Dordogne region of southwest France is the focal point of the time machine--where the "explorers" are sent. Meanwhile in modern times, a team of ITC-sponsored archaeologists uncover the remains of a medieval castle, village, and monastery in this same area. Like any good American corporate heavyweight, Robert Doniger of ITC sees the possible financial gain. Specifically, through a major tourist attraction.
While they are uncovering the remains, they find the words--in modern English--"HELP ME", followed by "4/7/1357". It is from the team leader--Professor Edward Johnston, an elderly Yale history professor--who has been secretly going back doing studies. Obviously he now seems to be in some sort of danger--thus the rescue effort begins. Five people are transported back to 1357--two bodyguard types and three historians from the Dordogne project: Andre Marek, student Chris Hughes, and his lover/instructor Kate Ericson. The time machine only allows them 37 hours for the rescue. Within minutes of arriving, both bodyguards are killed--leaving the three historians to find Professor Johnston. And the race against time thus beings.
The team learns that Johnston is being held captive by Lord Oliver, an English nobleman-warrior who is at war with the French and, in particular, with Lord Arnaut. Oliver has even captured Arnaut's sister, Lady Claire. The team soon finds themselves in the middle of this historic battle getting more than they originally bargained for.
In Timeline, Crichton has given readers like myself, that is to say, readers who read for entertainment--who are not looking for a teaching seminar--a somewhat believable possibility that Time Travel can exist--as far fetched as it sounds. Yes, there are holes in his science, but if you do not expect too much you can allow yourself to be caught up in the ride.
Just when you may start to lose interest in the novel, it goes into a different direction entirely--fourteenth century. The science lessons for the day are virtually eliminated from this point of the novel--and we have now entered a new area in which Crichton has decided he should teach us about--the medieval years. And what he gives is a somewhat darker--yet very realistic version--of this period. You will find no knights in shining armor here.
Although, this is a completely different twist to the normal Michael Crichton novel, it is written in a very Michael Crichton manner. For example, you will learn the details of how to joust properly. In more "normal" Medieval literature, this would be more of a heroic scene than what is presented in Timeline. The "heroic" here, is instead "historic".
In every Crichton story there is a character (representing Crichton himself) that teaches the other characters (representing us - the reader). Here it is Andre Marek--the closest thing this story has to a "hero". Marek is the expert of the group of the environment they are trapped.
Overall, Timeline is a fine novel - just keep your expectations somewhat lowered as it is by no means a classic.