In the strange village of Ulthar, a curious law forbids anyone from harming a cat. This decree exists because of a terrible event that proved the animals' vengeful spirit, an act of collective supernatural retribution against a cruel old couple who once took pleasure in killing the community's feline inhabitants. The cats of Ulthar vanished entirely the night a grieving young traveler passed through, and when they returned, the malicious couple had simply disappeared from the face of the earth.

This world is part of the Dream Cycle, a realm of fantasy and occult horror where reality merges with the subconscious. The manga follows three narrative arcs adapted from the short stories of H.P. Lovecraft. The title story, The Cats of Ulthar, serves as the thematic centerpiece, exploring how the elderly couple’s cruelty summons an unholy migration of felines who exact justice beyond human law.

Two other stories expand the boundaries of this dreamlike world. In Celephaïs, a man named Kuranes is consumed by an obsession with reaching a fabled imaginary city of eternal beauty. He is willing to risk the endless sleep of death itself to escape his mundane existence and become the king of his own dream domain, discovering that some dreams are more real than the waking world. Finally, The Other Gods follows Barzai, a wise and respected sage of Ulthar. Corrupted by intellectual pride, he ascends the forbidden mountain of Hatheg-Kla with his disciple Atal to look upon the faces of the earth gods. In violating this taboo, he learns that there are always greater gods lurking beyond the veil, waiting to cast down the overconfident.

Together, these arcs form a single thematic volume exploring hubris, illusion, and the inevitable defeat of men who seek to master the unseen spirits that govern the world. The narrative focuses on protagonists who are artisans of their own downfall, whether through cruelty, obsessive desire, or intellectual arrogance. The setting shifts from the dusty, cat-inhabited streets of Ulthar to the soaring, impossible spires of celestial cities and the frigid peaks where strange gods dwell, all rendered as a land where the boundary between dreamer and the dreamed is terrifyingly thin.