Honestly, I don’t remember if I read it or watched it. 
Anyway… an underage girl is living by herself in a New England town. Her parents are away or dead. She’s hassled by her landlady, and especially by her landlady’s son. She is befriended by a local bicycle riding kid who want’s to be a magician. At some point it’s hinted that bodies are down a trap door in the dining room.
Any ideas?
Thanks!
It’s The Little Girl Who Lives Down the Lane (1974), by Laird Koenig. It was also adapted into a movie with the same title (1976) starring young Jodie Foster.
Thanks! The mention of Foster brings it all back!