While running away from his disturbed mother and his empty suburban life, Hugh Rogers discovers a gateway into a magical forest world. There, where it is always twilight, he finds solace and belonging. Although he returns to reality, he crosses the gateway frequently to drink from the river and to recharge his spirit in the natural setting.
On one trip, he meets Irene Pannis, who also discovered the gateway while trying to escape her unhappy home life, which includes the threat of physical assault at the hands of her stepfather. Irene had been crossing over into what she calls the “ain” country for years. Like Hugh, she believes that she belongs here. She has made ties with the inhabitants of the mountain town of Tem-breabrezi, who represent family to her and the only real home she has ever known. She also harbors a secret love for the grim mayor of Tembreabrezi, Master Sark.
Irene is enraged to find Hugh in “her” place, but the two soon establish an uneasy truce, for they learn they need each other. Irene sometimes cannot get into the twilight world; Hugh cannot always get out. The townspeople need them too, for there is a goblin or monster haunting them, choking off their livelihood and holding them hostage. When Hugh arrives in Tembreabrezi, its residents take him to be their savior, the knight who will slay this dragon. Hugh is willing—he wants in particular to impress the fair-haired damsel Allia, with whom he is secretly in love. When Irene realizes that Sark would use her as an offering for the monster, she becomes disenchanted with the twilight world and joins Hugh in his quest.
Together, Hugh and Irene track the screaming, gobbling monster. Although in their first encounter with it they hide, cowering in fright, they gather their courage and follow the monster’s path to its lair. Irene baits it, and Hugh kills it with a sword. Hugh is seriously injured as the dying monster falls on him, and Irene must aid him as they find a way out of the labyrinthine twilight world and back to reality. In this final journey, they realize that they love each other and that in order to get on with their lives they can and must depend on each other. They vow to reconfigure their lives on the outside and not to return to the twilight world.