Carmine, a sewer worker for the city of Naples, finds himself working in the vault of the Bank of Naples one morning, and he gets the idea to pull off a robbery using the sewer system. To pull off the heist, he enlists the help of Gaetano, a former robber with several years in prison; the depressed Peppe "'o' Sciomen," a legend of the Spanish Quarter and also a former prisoner for robbery; the boxer Ruocco, a former professional who ended up fighting in clandestine matches; and Striano, a photographer and robber. After completing the robbery, however, Gaetano disappears without a trace with the million-dollar loot, leaving his accomplices locked in their lair, hoping to see him reappear. As time passes, strong tensions build between the four, bringing out old misunderstandings and fracturing alliances, until a new threat looms on the horizon: the powerful boss Jannone demands a share of the loot they don't yet have.