Vivian brings in her new pet mouse, Nugget, to meet everyone. Nugget accidentally gets loose in the box and hides. The kids jump into a picture, from Vivian's picture box, to ask a cool cat for some mouse finding tips. They make Nugget a little mouse house out of everyday objects and set out a mouse trail of mouse snacks for Nugget to follow. They play out their own version of "The Lion & the Mouse." Nugget returns and Vivian takes her home where she'll be safe in a proper mouse house.