Clockwork Key - Vashti Hardy;Rebecca Sheerin

Using an ancient map, they are searching for the legendary lost town of Umber, famous for the invention of clockwork, which was mysteriously abandoned hundreds of years ago. The only other clue they have is a strange old key left behind by the last inhabitant of the town, but they have no idea what the key is for.

Also on the hunt for Umber is devious Byron Cogsworth, who is desperate to claim the glory such an important discovery will bring. Can Mabel, Will and Aunt Lucy find Umber before him? And what secrets will the clockwork key unlock?