Caroline Hartley has a magic key. It has allowed her and her brother, Martin, to secretly step through an attic door and time-travel back to 1912, at the castle they have been staying at in central Europe. Unfortunately, bad weather in the present has forced them and their father, Chris, to leave the castle and go back to Bratislava. The Hartley children would love to return to the castle as they would like to use Caroline's magic key again. Both wish to time-travel back to 1912, where they can meet their friends, who have invited them to see the inspection of the fleet in Trieste, Austria-Hungary. Caroline is currently unsure if this will be possible.