Christopher is astonished to discover that gargoyles Ambergine and Gargoth are living in the park next door and that Katherine, a girl from his class, knows the gargoyles, as well. When the Collector steals Ambergine, it's up to Christopher and Katherine to get her back, as long as something else doesn't catch them along the way.

Christopher has a problem. He has just moved to Toronto. He has a new school and no friends. But even worse, the park next door is creepy: voices whisper in the bushes, and something throws apples at his window and howls at the moon. But what? Gargoyles! Their names are Gargoth and Ambergine, and they need help. An evil thief called the Collector is after them and wants to lock them away in his dark mansion, forever.

Befriending a gargoyle takes courage, but it's worth it. Once he does, Christopher suddenly has more friends than he ever imagined, including Katherine, a girl from his class who knows the gargoyles, as well. When the Collector steals Ambergine, it's up to Christopher and Katherine to get her back, as long as something else doesn't catch them along the way.

This is the third book in the award-nominated Lost Gargoyle series.