"You're my dad." That's the first thing teenager Cass Reilly says to Dom after crashing his housewarming party. The boy is not his son, but could throw Dom's life into complete disarray by exposing his false identity. Cass agrees to let Dom be if he helps find the killer of the real Dom Reilly. He wants to kill him. That leads Dom and Cass to Reno and then to Detroit where he encounters Cass's larcenous mother, his mob-connected family and eventually the killer himself. Dom struggles to keep the kid from murdering anyone while trying to protect the life he loves.