Bleakwatch Chronicles: Tinker Bell and the Lost City

"Tinker Bell loves nothing more than solving a problem. For her, red buttons demand to be pushed, treasure maps need to be followed, and lost things ought to be found. So when a strange fairy crash lands in Pixie Hollow and leaves Tinker Bell two clues to find a mysterious necklace on the Mainland, she really doesn't have a choice but to help. However, her journey takes an unexpected turn when she discovers a hidden city of fairies living below the streets of London"--