Upon the vessel "Machine Gun Kelly", a casino owned by the mafia that is situated on water, Zenigata emerges. His aim is to hinder Lupin from embezzling the casino's cash. Although Lupin and his associates successfully accessed the ship's vault, they were thwarted in their attempt at making off with the money by Zenigata's gunfire. It becomes evident to Lupin that the vessel had another purpose, one that he was privy to; locating a sunken ship brimming with gold. While aboard the ship, he absconds with this information. Nonetheless, Lupin now finds himself in the midst of Zenigata, the mafia, and a clandestine organization whose headquarters lay beneath Alcatraz. The group endeavors to unravel the organization's secrets and to unearth the treasure below the waves.