The Night Door (Edison Beaker, Creature Seeker Book #1) (graphic novel)

Edison Beaker and his young sister Tesla are staying with their uncle Earl, manager of the family pest control company, when an alarm sounds and he has no choice but to drag them along on a service call. They should have listened when he warned them, “stay in the van.”

Monster-sized mayhem ensues when the kids chase their escaped hamster into a mysterious warehouse–and suddenly they are the ones being chased as all sorts of creepy creatures scurry, slink, and stomp through a secret Night Door.