After several criminals teamed up to kill Mystery Inc. for putting them behind bars, Shaggy and Scooby were left the only survivors having ran and hid while their friends walked into the trap. Consumed by guilt, Shaggy fell into a cycle of drug abuse and mental illness, obsessed with taking care of the Mystery Machine. When the son of one of their old enemies finds them years later, kills Scooby and steals the Mystery Machine, Shaggy finally snaps. He seeks out old allies who once unlocked his inner strength, and begins on a mission of vengeance.
