Mike Blair had spent years investigating the worst days of people’s lives. Then, in March 2018, inside a room at Tampa General Hospital, the homicide detective met an 8-year-old boy he couldn’t forget. Ronnie Blair lay in a bed, his small body wrapped in bandages after surviving an unimaginable act of violence that had taken the lives of the two people he loved most: his mother, Kenyatta Barron, and his 9-year-old sister, Ron’Niveya. Two weeks had passed since the attack, and visitors streamed in and out of the room, trying in whatever way they could to help. For reasons no one who was in the room can fully explain, Ronnie focused on one of the detectives. As Mike prepared to leave, the boy reached for his hand. Would he stay and watch a movie with him? Mike told him he couldn’t. He had to return to work. But he made a promise. That night, after his shift ended, Mike returned to the hospital with his wife, Danyel. Together they sat beside Ronnie’s bed and turned on a “Power Rang...