MYSTERY OF MORDACH CASTLE - Used Hardback

A super creepy novel for young readers by William MacKellar and beautifully illustrated by Jerry Lazare. This hardback appears unread with a tight spine. It was published in 1970. What may make this book even creepier is that there's a kid's name on the inside front cover, then on the inside back cover there is weird and cryptic formulas written by a young girl. Very strange.