A strange mob has crash-landed in the Overworld, and the news warns it might be from the Moon. Then Zombie and his friends meet Crater, a new student at Scare School who looks like no mob they’ve ever seen before. Zombie is convinced that Crater is the mob from the Moon, so he befriends him to uncover his secrets. As it turns out, becoming Crater’s friend is the easy part ... and stopping what comes next is the real challenge.