Boon is an elder craftsman of ghost masks, which are said to be vessels for the dead. After dreaming of his missing daughter, Lalita, calling for help in the forest, he's unaware when her spirit enters his latest piece. When travel content creator Thianphisut visits the Phi Ta Khon ghost festival in Loei with her boyfriend Rachen, she purchases Uncle Boon's blue mask and is possessed by Lalita's spirit. In this new form, Lalita meets her former lover Chatban, and he feels an uncanny familiarity.