Xiaobao's grandfather was a mask craftsman in the village. His house was full of masks which was the adventure paradise for Xiaobao. Xiaobao enjoyed watching his grandfather paint masks and listening to his stories about masks. However, at night, these strange and scary masks seemed to look like monsters in the dark which gave Xiaobao many sleepless nights. On the Lantern Festival Day, Xiaobao went to the ancestral temple where he saw God of the Mountain leading other gods in a group dance. Soon God of the Mountain invited Xiaobao to join the dance. Xiaobao was very nervous but very excited at the same time! The group danced around the village for a long time before quitting. Xiaobao was surprised to find that God of the Mountain was his own grandfather who was covered with the mask. His grandfather was truly God of the Mountain for Xiaobao who protected him and gave him love and courage. He slept soundly that night and was no longer afraid of the darkness. The artist uses simple and childlike brushwork in the book to show the mysterious mask art and culture and also to convey the deep love between the grandfather and his grandson.