The Glacius spellbook is a book contaning information and instruction on the Glacius spell. It was owned by Professor Remus Lupin, who used it during one of his Defence Against the Dark Arts classes with the third year Gryffindors. He placed the spellbook within a secret passageway underground, and asked Harry Potter, Ronald Weasley and Hermione Granger to retrieve it and return it to the classroom, which they did. Hermione was the one who found the book..