The House on Hoarder Hill by Mike Lish & Kelly Ngai

When Hedy and Spencer start receiving messages on dusty picture frames, Christmas at their grandfather's spooky house turns into a mission to solve the mystery of their grandmother's disappearance. What is their magician grandfather not telling them? With the help of a (talking) mounted stag head, an (also talking) bear rug, and other (currently) disembodied spirits, and against the resistance of gargoyles and ravens, Hedy and Spencer set out to find the truth.

Dog Gone note: This book is in excellent condition.