A deep-sea diving trip at one of the world's most remote spots becomes a fight for survival for sisters Drew and May when a catastrophic landslide sends rocks tumbling into the sea. After being struck by the rockfall, May now lies deep below the surface, trapped by debris and unable to move. With dangerously low levels of oxygen, it is up to Drew to fight for her sister's life. She must put her own life in jeopardy and risk paying the ultimate sacrifice. With no help in sight, time is quickly running out.