What Lies Below (2020) is a tense sci-fi horror thriller that masterfully blends family drama with unsettling supernatural dread. The film follows 16-year-old Libby, who returns from summer camp to find her mother, Michelle, deeply involved with a new man named John Smith. While John appears to be the epitome of charm, intelligence, and physical perfection, Libby's intuition screams that something is profoundly wrong. His behavior is just a little too calculated, his presence just a little too unnerving, leading to a creeping suspicion that he may not be human at all.

Director Braden R. Duemmler builds suspense through a slow-burn narrative, focusing on atmospheric tension and psychological unease rather than overt gore. The performances are key to the film's effectiveness; Ema Horvath delivers a compelling turn as the perceptive and increasingly isolated Libby, while Trey Tucker is genuinely unsettling as the enigmatic John. Mena Suvari provides a grounded performance as the mother caught between her daughter's fears and her own desire for connection.

While the film's IMDb rating of 4.4 suggests a divisive reception, it has found an audience among viewers who appreciate its unique premise and sustained mood of paranoia. The 87-minute runtime ensures a tight, focused story without unnecessary filler. For fans of psychological horror and sci-fi thrillers that explore the monstrous hiding in plain sight, What Lies Below offers a compelling and chilling watch. Its strength lies in the relatable fear of a loved one being deceived by a dangerous imposter, making the supernatural threat feel uncomfortably close to home.