Katie has bought a box of chocolates for her mom's birthday, but when they go to open it the box is missing, and Katie and Pedro set out to track down the thief.
When Katie's father looses his special rainbow ring while playing with the kids in the backyard, Katie and Pedro work to follow the clues to find the missing ring.
Pedro and his dad are walking Katie home on a foggy night when they are seemingly pursued by something very smelly, and Katie and Pedro try and solve the mystery of the big smell.