Sabotaged — Margaret Peterson Haddix

After helping Chip and Alex survive 15th century London, Jonah and Katherine are summoned to help another missing child, Andrea, face her fate. Andrea is really Virginia Dare, from the Lost Colony of Roanoke. Jonah and Katherine are confident in their ability to help Andrea fix history, but when their journey goes dangerously awry, they realize that they may be in over their head. They've landed in the wrong time period. Andrea doesn't seem that interested in leaving the past. And even worse, it appears that someone has deliberately sabotaged their mission...