The Emerald Key — N.R. Wick

Nine year old Holly Greene is bored, bored, bored! Her nanny Madeline knows just how to fix that with a special surprise hidden away in a dusty attic. While looking for Maddie's treat, Holly discovers an ornate key garnished with emeralds. But she may have gotten more excitement than she bargained for when the key opens a mysterious trapdoor in the garden. Trapped in a fantastical place where nothing is quite as it seems, Holly must find the courage and smarts to return home.

The Emerald Key is a short story for middle grade readers and is part one of the Keepers of the Gemkeys.