Kristina Miller witnessed a Russian mafia execution right after her diving rounds as one of the Poseidon Hotel’s staff. This event leads her into meeting the Russian godfather, Lucas Romano. The next thing she knew, a gun is about to blow her head off – or so she thought. A tsunami hit a coastal city, trapping a group of people inside the newly opened Poseidon Hotel situated 50 meters down the surface. Kristina along with Lucas and his men are swept off inside the hotel together with three tourists and four hotel staff, but it turns out that they have room for one more guest. What was once a hotel for the elite becomes an inescapable death trap along with a 12-foot great white shark. Will they be able to find their way out when they are 161 meters submerged with water together with an apex predator? What will Kristina think of the ruthless mafia godfather when his foul words contradict his action every time he helps her?