The members of the balloon team have fled to the submarine of Captain Nemo. Their lives are in great danger, threatened by the pirates. These buccaneers can not afford anyone witnessing their misdeeds. Captain Nemo's divers succeed in blowing up the pirate ship after the pirates land. But they manage to get on the Nautilus and shoot Captain Nemo. Suddenly the volcano erupts and the balloon crew has to flee the submarine when a ship appears on the horizon.