White (The Circle: Book 3) by Ted Dekker
Time Is Running Out In Two Realities.
In one world, a lethal virus threatens to destroy all life as scientists and governments scramble to find an antidote. In the other, a forbidden love could forever destroy the ragtag resistance known as The Circle.
Thomas can bridge both worlds, but he is quickly realizing that he may not be able to save either.
In this mind-bending adventure, Thomas must find a way to rewrite history as he navigates a whirlwind of emotions and events surrounding a pending apocalypse.
The fate of two worlds comes down to one man's choice--and it is a most unlikely choice indeed. Life. Death. Love. Nothing is as it seems. Yet all will forever be transformed by the decisions of one man in the final hours of the Great Pursuit.