When Dennis’s parents are invited to an adult-only wedding, he and Harsha devise the perfect plan to avoid nagging babysitters: they’ll do it! However, when Dennis’s little sister Bea goes missing, they’ll start to realise that babysitting isn’t all it’s cracked up to be! Join Dennis, Gnasher, Harsha and Rubi as they chase Bea across Beanotown, following the trail of destruction she leaves in her wake. Will they find her before Dennis’s parents get home?