Meet Mary McScary! She doesn't say boo. She says "BOOOOOOOOO!" Mary spends her days being scary. She scares her mum, her dad, her pets, and even a balloon! But Mary has met her match when her cousin Harry McScary comes to visit. He's not afraid of anything, until Mary finds a way to give Harry the scare of his life... A wildly funny new picture book by the award-winning talents behind GOOSEBUMPS and ARTHUR.