CYCLE OF THE WEREWOLF
by Stephen King
4 stars

This is a very short story about 1 hr to read. Book is 127 pages with plenty of pictures, so maybe 50 reading pages.
Small town is terrified by a werewolf for 1 yr. Each month is it's own chapter with 2 to 4 pages. This is for a 10 to 13 year old just getting interested in this kind of thing. Hero may be surprising, villain isn't. By chapter 6 June, you should have figured it out.