Captain Flatus Codswallup needs ten-year-old Lucas’s help getting his sewer-sailing ship seaworthy, and flushes him as a new recruit. Lucas learns it’s not all toots and giggles as a sewer pirate. But when the ship is attacked, Lucas learns who Flatus’s enemies are. Plumbers like Dad! Now Lucas has to choose a side as plumbers and pirates meet in the messiest battle the sewers have ever seen.