In ancient Rome, the slaves are rebelling - and they've even stolen Julius Caesar's own warship, the finest in the Roman navy. Under the heroic leadership of Spartakis, the former galley slaves make for the small town where Caesar's old enemies Asterix and Obelix live. When they arrive, though, the slaves find the town in crisis because Obelix has drunk a magic potion that has turned him back into a child. Now everyone must sail to the wonderful continent of Atlantis to find a cure. But, the Romans are on the ocean blue, too...and the battles are about to come fast and furious.