Art and his family are invited on a fantastic free holiday to the exotic Asteroid Belt - in a remote part of space near Mars. Taking the train, they arrive to discover that nothing is quite as it seems - the hotel slips curiously back and forth through time, and the guests behave rather strangely, too. What is behind these bizarre goings on? It's up to Art, Jack Havoc and his sister Myrtle (against her will) to get to the bottom of things. But the giant sand clams and man-eating starfish which roam freely nearby are nothing compared to the True Enemy, which is cunning, sinister, and almost unstoppable, and may resemble a hat ...