The Case of the Mysterious Future

Grace and Jack are still trying to come to grips with their timetravelling experience as they eagerly await their next adventure.
After making a promise that they'll always travel together, Grace is unexpectedly transported into the future, alone and scared. How did she get there? And more importantly, how can she get back without Jack there to help?
Picking up clues as she goes, Grace must try to navigate this new Miller's Island and somehow figure out what sent her there in the first place.