What Lies Below (2020)

A socially awkward teen finds her world turned upside down when her mother brings home a charismatic new fiancé. At first, his striking looks and intellect captivate her, but as unsettling events unfold, she starts to suspect that this seemingly perfect man harbors dark secrets. The teen must navigate her growing unease and uncover the truth behind his charming facade before it's too late, leading to a chilling revelation that challenges her understanding of family and trust.