The Eight is a novel by Katherine Neville. It is set in all sorts of places, notably France, the USA, Algeria, and England. The story weaves the time of the French Revolution with the 1970s. There is an ancient chess set that once belonged to Charlemagne, which contains some sort of secret powerful formula. There is a GAME being played .... and the narrator is chosen to join it!
It is a thriller, meticulously researched, with beautiful descriptions, women caught up in larger-than-life adventures, and good vs. evil in a BIG way.