In 1975 an army of gigantic crabs, the result of an underwater nuclear experiment, attacked the Welsh coastline. The battle was bloody, many lives were lost until the crustacean invaders were defeated. Over the ensuing years they turned up in the oceans of the World with further terrible slaughter of humans. Finally, though, it was believed that these monsters from the deep had been eradicated. Only memories of their invasions of land remained...