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. But as small acts of mischief escalate into a vicious battle, Lord Blackheart realises that Nimona's powers are as murky and mysterious as her past ... and her unpredictable wild side might be more dangerous than he is willing to admit.