Nimona is an impulsive young shapeshifter with a knack for villainy; Lord Ballister Blackheart is a villain with a vendetta. As sidekick and supervillain, the pair are about to wreak some serious havoc. Their mission: prove to the kingdom that Sir Ambrosius Goldenloin and his buddies at the Institution of Law Enforcement and Heroics aren't the heroes everyone thinks they are.