While watching a scary show a kid discovers his dad is really a robot./Tommy climbs in a bag and ends up at the post office where he's mistaken for a piece of mail.
The adults blame Spike for mysterious accidents in the garage, but Tommy believes his pet is innocent. Convinced the accidents are caused by a monster, Tommy talks the other Rugrats into a garage expedition.
Angelica convinces the babies to give her their candy or they'll turn into whatever they dress up as. Chuckie finds his inner werewuff and stands up to Angelica.