The Chime Seekers by Ross Montgomery

The Chime Seekers tells a powerful emotional story, drawing us into a playfully imagined world inspired by aspects of British folklore and also perhaps a touch of Jim Henson's Labyrinth. Yanni, a boy struggling to accept his baby sister and his family's move to the countryside, stumbles into a parallel world ruled by a malicious fairy. He is joined by Amy, his nerdy cousin whose knowledge of all things fantastical will come in useful. Yanni and Amy must complete a series of quests, wagers made with the evil fairy king, to win back Yanni's baby sister before she is transformed into an evil fairy. Their first task invovled infiltrating a castle full of big, dim-witted goblins...

Read Mark's list Goblinalia: favourite books featuring goblins

https://uk.bookshop.org/lists/goblinalia