The Ghoul in the Glossary by Michael Dahl
A school basement is packed with towering bookshelves, and it's a dream come true for two students. But then they discover drops of ink dotting the shelves. Something skitters in the dark. A ghoul is on the loose. Can the Librarian banish the creature before it sucks every last book dry? Uncover hidden dangers and dark mysteries with SECRETS OF THE LIBRARY OF DOOM, a page-turning chapter book series from bestselling author Michael Dahl.