In a search for the truth behind her twin sister Piper's mysterious disappearance, a tenacious Iris Walsh delves into the chilling depths of Shoal Island Hospital for the criminally insane. A once-cold case reignites as Iris braves her own internship among society's most dangerous minds, seeking the elusive proof of Piper's fate. As shadows loom and secrets threaten to surface, Iris's quest becomes a harrowing journey through a sinister world that watches unceasingly.