Deep within the murky depths of New York harbour something is stirring. After the mysterious disappearance of a young couple from a pier, police divers discover their mutilated bodies...who or what could have caused this grisly mutilation? The elite underwater police division of New York led by Sgt Nick Holifield are about to find out as they try to recover the bodies... Nick senses something is watching them. The next night a small tugboat mysteriously explodes and sinks to the bottom of the harbour. July 4 celebrations are only two days away and the harbour will be crammed with thousands of boats and people, panic has already set in with the reports of the unexplained accidents. No one dare believe that these were no ordinary accidents but a deep sea monster may exist and lays on the sea bed deep below the murky waters of the New York harbour. No one even wants to believe that a subterranean terror is about to unleash it's horror...how wrong can they be!