So-yeon is a young woman who suffers from claustrophobia, a debilitating fear of small spaces. She lives alone in a small apartment, where her only companion is a goldfish named Jjoong-bi.
One day, So-yeon inherits a Persian cat named Silky from the estate of an elderly woman who has passed away. Despite her fear of cats, So-yeon decides to keep Silky and slowly becomes attached to the affectionate feline.
However, as she begins to unravel the mystery of Silky's previous owner, So-yeon begins to experience terrifying nightmares that leave her feeling as though she is being suffocated. The nightmares involve a small, dark space in which she is trapped with a malevolent presence that seems to be trying to kill her.
As So-yeon investigates the disappearance of Silky's owner, she discovers a link between her claustrophobia, her nightmares, and the deaths of several people who had contact with Silky. So-yeon must confront her fears head-on in order to unravel the mystery and save herself from the same fate.
