In My Father's Basement: a serial killer novel

The first 75 pages of this were extremely slow. NOT a slow burn, just dragging & boring. Isaac is a serial killer's kid and hasn't seen his dad since he went to prison. He's barely making it by selling serial killer memorabilia on the internet to survive. A prison guard has a proposition for him to make some money. He will get Isaac into the prison to see his father and record the conversations to sell. Isaac's dad has never explained why he killed so many people or how he did some of the murders. Isaac goes to see him and the story SLOWLY unravels. Back and forth conversations, a side story that had loose ends, a slight romance, a murder, and unanswered questions by the end of the book. The book felt rushed the last few chapters and didn't really end that great.