Scrunt is a grass-covered wolf-like monster with venomous fangs that lie preternaturally flat. It is very difficult to detect, only a mirror allows to see its red eyes. It generally attacks the aquatic nymph-like creatures called Narf when they are out of water, unless if they return to their home, the Blue World. If Scrunt transgresses this law, the Blue World's peacekeepers called Tartutic, which are a trio of powerful simian creatures, will severely punish him. They also can be stopped by persons which are the Guardians of the Narf.
After a Narf named Story leaves the Blue World, a Scrunt discovers that she is destined to become the new leader of the Blue World and decides to track her. He finds her in the pool of a Philadelphia apartment complex and tries to attack her, but a caretaker named Cleveland Heep finds her and manages to rescue her from the Scrunt's attack.
The following evening, Story tries to return to the Blue World with the help of a giant eagle named the Great Eatlon, but the Scrunt attacks her before the eagle's arrival and gravely injures her with his venomous fangs, thus transgressing the law. However, she manages to escape and Heep helps her to heal.
During the next evening, Heep, which Story thinks that he is his Guardian, comes to confront the Scrunt. He tries to arrest the monster and to make him run away, but it doesn't work and the Scrunt attacks and nearly kills him, though he manages to survive.
One day after, Story, Heep and some other residents develop a plan to allow Story to return to the Blue World with the Great Eatlon. One of the residents keeps an eye on the Scrunt with a mirror during the practice of the plan, but things go wrong and Story is mortally wounded by the Scrunt. Later, he manages to enter in the building and kills Harry Farber. Soon after, he sees Story, which has been healed by Heep, near the pool waiting for the arrival of the Great Eatlon along with Heep and the other residents. The Scrunt attacks them, but Reggie, one of the residents, is revealed to be the true Guardian and manages to stop the monster. The Great Eatlon arrives immediately after but its cry distracts Reggie, which releases the Scrunt. However, before he could attack Reggie and the others, the Tartutic arrive and drag him away, then kill him.