In 1972, in a remote village in Kanchanaburi Province, a young girl mysteriously died just days after hearing a strange, repetitive sound resembling "Tee Yod" during the night. The tragedy quickly spread through the small community, prompting her older brother Yak (portrayed by Nadech Kugimiya) to leave his military post and return home to care for the family. One day, Yak's younger sister Yam (played by Tisanart Sornsuek) encountered an eerie woman dressed in black on her way home from school. Following this encounter, the once well-behaved Yam began exhibiting a sudden and alarming change in behavior. As her condition worsened, she frequently engaged in inexplicable and bizarre actions, leaving those around her deeply unsettled.