Deep within the enchanted woods in the town of Watch Hollow stands the once-grand Blackford House, whose halls hold a magical secret: a giant cuckoo clock that does much more than tell time. But when the clock's gears cease to turn, an evil presence lurking among the trees begins to come out of the shadows. When Lucy and Oliver Tinker arrive in Watch Hollow, they have no idea that anything is wrong. A mysterious stranger has made their father an offer that's too good for him to refuse. All Mr. Tinker needs to do is fix the clock at Blackford House and fistfuls of gold coins are his to keep. It doesn't take long, however, for the children to realize that there is more to Blackford House than meets the eye. And before they can entirely understand the strange world they've stumbled into, Lucy and Oliver must join forces with a host of magical clock animals to defeat the Garr--a vicious monster that not only wants Blackford House for itself, but also seeks to destroy everything the Tinkers hold dear.