A year after their adventure as monsters, The Wishbones are back living their normal, human, lives, which are filled with all the usual quarrels, stresses, and everyday madness that family life brings. However, a surprising encounter with Mila Starr marks the beginning of a new adventure that makes all their ‘normal’ problems fade away. Mila, a battle-hardened, mini-agent, unexpectedly shows up at Baba Yaga and Renfield's wedding, kidnaps the couple, and thus leaves the Wishbones with only one option to save their friends – they must once again transform into their monster alter egos. As a Mummy, a Werewolf, a Vampire and Frankenstein's monster, they pursue Mila across the globe to prevent her from kidnapping more mystical creatures. However, Mila’s monster hunting turns out to be just one piece of an elaborate puzzle and it’s her parents, Marlene and Maddox, who are the real puppet masters calling all the shots.