Sabotoged

Sabotaged by Margaret Peterson Haddix
Sabotaged is the third book in the Missing Series. In this book, Katherine, her brother, and Andrea are sent back in time. Andrea messes with the eulicdator and they end up in the wrong time. This was set up by Second. Seconds goal is to "fix" time. In the end, Second succeeds and the author sets it up for another book, because now Jonah and the rest of them must stop the time ripple.