Someone's Knocking at the Door / The Deep Ones

THE DEEP ONES - A married couple rents a beach side Airbnb only to be surrounded by peculiar neighbors and occurrences. They soon discover that they are in the grip of a mysterious cult and the ancient sea god that they worship. SOMEONE'S KNOCKING AT THE DOOR - Returning to the medical school where they were test subjects decades ago, a pair of outrageously twisted serial killers use shockingly brutal sex acts to start killing off a group of drugged-out med students.