Bell Bandit

The Bell Bandit by Jacqueline Davies 

Grandma's house has burned down. They try to make the trip out there similar to what it has been, but it is not the same. The boy ends up helping the handyman to fix it. The girl becomes friends with an autistic boy next door. They try to find what happened to the missing bell that is always rung at new years. They also work have some encounters with the "bad boys" who they see torturing frogs. Grandma occasionally loses her mental capacities. One time they find her outside in a teepee in the snow, thinking it was a bus stop taking her to class. The boy pretends to be from the bus company to get her back. By new years, they have discovered the bell - the autistic boy had hid it at his house to keep the mean boys from taking it.

The characterizations of the autistic boy and the senile grandma feel too stereotyped.