How to Kill a Monster — R.L. Stine

HOME ALONE... WITH A MONSTER?
Gretchen and her stepbrother, Clark, hate staying at their grandparents' house. Grandpa Eddie is totally deaf. And Grandma Rose is obsessed with baking. Plus, they live right in the middle of a dark, muddy swamp.

Things couldn't get any worse, right? WRONG.

Because there's something really weird about Grandma and Grandpa's house. Something odd about that room upstairs. The one that's locked. The one with the strange noises coming from it. Strange growling noises...