Looking for horror book name where villan was badly burned and locked up by his father

[Rachel]

The book was horror, and about a man who was previously in a mental hospital after his family died in a fire. From what i remember he has the son of a rich guy (who was part of a strange sex cult) after him beacuse when he was young the son pf the rich man came into his house to kill the family and the boy set the place on fire. In turn the rich father locked up his badly burnt sound for like 15 years.

Does this sound familiar to anyone? Thanks!