Take the helm of a Nautilion submarine and recruit a heroic crew to vanquish the treacherous Darkhouse that lurks in the oceanic depths. You must get to the Abyss, lair of the Darkhouse, before the Phantom Submarine (his henchman) reaches your homeland, the Happy Isles — but to defeat the Darkhouse, not only must you be faster than the Phantom Submarine, you must also assemble the submarine's crew along the way.