A city-dwelling couple and their friend are invited to the remote tidal island of Amen for a surprise birthday party. Husband Rick has been in cahoots with Corinne, an enigmatic Amen Island local who he believes holds the answers to his wife s long-buried family secrets. But the surprise birthday trip soon goes horribly wrong and the trio find themselves trapped by the tide and at the mercy of the unwelcoming island community. A growing sense of unease turns into a living nightmare for the visitors as the true horror of the situation unfolds.