The Harvest

Maryann moves in with her grandparents after she's orphaned. Desperately lonely, she sets out to befriend a neighboring deathly ill, bed-ridden boy, despite the outright disapproval of his mother. Maryann's persistence pays off, however, and during a series of secret visits she gradually uncovers some seriously sinister goings-on in the house.
First the Fall, then The Harvest.