Set in the current day.
A secret society known to themselves as "The Brethren" ("The Tabula" to their enemies) have, for centuries, been trying to create the perfect, ordered, worldwide society. Their greatest threat has always been The Travellers. A Traveller has the ability to leave their own body and see other realms, they can see the world for what it really is, beyond the obvious. Travellers are forces for change, they cannot conform to the machine of human society once they see beyond. The Brethren have hunted the Travellers for centuries, but the Harlequins standin their way. A gypsy-like society sworn and trained from birth to do this one task, the Harlequins are seen as a force for anarchy.
The story follows a woman Maya, who abandoned the path of the Harlequin, to her father's great disappointment. The Harlequins are nearly extinct, and Maya falls into a Tabula plot to find the last Traveller.
I probably did a poor job describing it, but you can find out more here:
http://en.wikipedia.org/wiki/The_Traveler_(novel)