Where's My Shoggoth?

A young boy wants to take his pet shoggoth for a walk — but, oh no! The shoggoth has escaped! Fearing for the safety of the poor thing, the boy sets out to find it, accompanied only by a small black cat. On the way they explore the rambling mansion and its grounds and encounter a number of creatures and demigods. Unfortunately, none are the shoggoth! Where, oh where, could his poor shoggoth be?