Journalist Billy Jensen spent 15 years investigating unsolved murders. Every story he wrote had one thing in common - it didn't have an ending. The killer was still out there. But after the sudden death of a friend, crime writer Michelle McNamara, Billy became fed up. He came up with a plan. A plan to investigate past the point when the cops have given up. A plan to solve the murders himself. And Billy gives you the tools - and the rules - to help solve murders yourself.