When Barney's rent money goes missing and he is threatened with eviction, Nev and Keith use the gizmos, gadgets and disguises in their new spy kit to do some undercover detective work. Using special binoculars, invisible ink and a skeleton key, they must act quickly, as Angry Pants is delighted at the news of Barney's imminent departure and has spotted an opportunity to use the space to expand his secret ice-cream business.