Middle School is finally over for Grace Brooks and she couldn't be happier for her graduation. All that lies between Grace and high school is one final summer. And what a summer it is as Grace and Jack discover yet more deeply hidden secrets and embark on their most unusual trip to date.

When Jack takes one too many secret trips, he finds himself facing the very real possibility of running out of time altogether. Can Grace gather her wits and figure out how to save him from the Treacherous Tunnel before time is up?