This episode takes place in an Australian sand castle tournament. The general premise is that a coral monster is kidnapping the sand castle builders however things are not as they seem as we learn in at the end. Suspects include a very loud band that knocks down sand castles with their loud music, two surfers, and all of the sand castle builders. One partially explained scene that left me confused after Velma solved the mystery is when Scooby and Shaggy are almost dragged into the sea by seaweed and then a rubber tube is found. Velma at first thinks this tube came from the monster, but then it becomes clear that it came from a pair of upside-down surfers. As always, Fred's plan ends up something along the lines of "Run!" although this time he doesn't need a trap to catch the criminal.