Alohomora spellbook

"However, I do remember reading somewhere that the Alohomore spellbook is kept in the library - I've heard there's a shortcut to the library down THAT corridor."

- Hermione Granger says to Harry Potter where is located the spellbook.

The Alohomora spellbook is a book that contained information on the Unlocking Charm. It also contained the instructions on how to perform the spell.

During his first year, Harry Potter, Ron Weasley and Hermione Granger were trapped in the Third Floor Corridor, by Draco Malfoy. Then, the trio was blocked by a locked door. Hermione asked Harry to use a secret passageway, for go in the library and find the spellbook. When he came back, Harry unlocked the door, and the trio discovered Fluffy. During his second year, Harry could buy the spellbook, at Fred and George's shop.

Appearances

 * Harry Potter and the Philosopher's Stone (video game)
 * Harry Potter and the Chamber of Secrets (video game)