Kyungsoo has left Severance to live with Jongin, leaving his old friends behind, but that's when things take a turn for the worst. Something in Sehun cracks and one of the employees of Severance Psychiatric Hospital ends up dead. They invite Kyungsoo and Jongin back to help Sehun, but will Kyungsoo be able to actually figure out what happened to him, or will he be forced to watch one of his best friends slowly unravel?