Admiral Horatio Nelson passes away, but not before urging Britain to build a larger navy with more men and, in a strangely intimate moment, asking for a kiss to Hardy. The scene sets a tone of swagger and luck that frames the rest of the adventure.
Albert Poop-Decker has toiled for eight and a half years and remains unqualified as a midshipman, yet the First Sea Lord recognizes the urgent need for officers and promotes him. Poop-Decker is ordered to join the frigate HMS Venus at Plymouth, where the mood is festive because the crew is celebrating their imminent voyage. He clambers into a sedan chair with no bottom—requiring a run by a lad and his father to Dirty Dick's Tavern.
Inside, Poop-Decker is swept off his feet by a chorus of admirers, with women mobbing him as he waves a sovereign “as advised by Dale.” He is saved from the melee by the quick intervention of Sally, a serving maid who has her own plot in mind. Sally wants to find Roger, her former lodger and childhood sweetheart, but Ned, the tavern keeper, has let her down. When she learns Poop-Decker’s not yet reported to the Venus, she devises a plan: upstairs she knocks him unconscious, dresses him in a midshipman’s uniform, and brings him downstairs.
Poop-Decker wakes to discover he’s dressed as a midshipman, and the pair descend into a raucous world of disguise and mischief. He is pulled into a conspiracy when, in a room below, he meets the press gang led by Jonathan Howett, the Venus’s First Officer, and his bosun, Mr. Angel. They are drifting toward sea when Howett and Angel reveal their plan to put Poop-Decker to use as a disposable pawn to push the Captain off the ship. The shipboard ruse works long enough for Sally, Poop-Decker, and the ever-loyal Walter Sweetly to expose the ruse and swap roles, with Sally openly revealing her true identity to Poop-Decker after he takes his punishment. Romance blossoms despite the chaos, and the pair begin to fall in love.
After three long months at sea with little action, restlessness grows among the crew. When they finally spot a Spanish ship, the Captain orders the Venus to withdraw, a move that leaves Howett and Angel plotting revenge. They stage a night raid to simulate an enemy boarding and use Poop-Decker as the foil to force the Captain to leave the vessel of his own accord. Poop-Decker, Sweetly, and Sally outwit them, helping the Captain escape into a launch.
On dry land, the Captain Captain Fearless suffers a splinter in his foot that festers into gangrene, and the group mistakenly believes they’ve landed in France rather than Calais—actually they’re on Spanish soil. Sally and Poop-Decker strip a bathing party of their clothes, enabling them to blend in and take stock of their next moves.
Back at sea, Howett and Angel advance toward Cádiz, aiming to seize the city from Don Luis, the Spanish Governor. Poop-Decker’s team arrives first, and their bold intrusions in Cádiz lead to a brief recapture of the Venus after they mistakenly think Le Havre is Cádiz. The voyage home becomes a new test as they encounter a pirate ship, and the crew is seized by Patch, a notorious captain who is revealed to be Roger, Sally’s long-lost love. Roger’s brutal drift from chivalry to rogue outfits the pirates, testing Sally’s loyalties.
Patch and Hook, the pirate’s ruthless second-in-command, attempt to force Poop-Decker and Fearless to walk the plank. Poop-Decker escapes, cutting down a sail and letting it drop across the criminals, neutralizing them and capturing their crew.
The voyage continues to Cádiz, where the Venus’s former crew are condemned as criminals but manage a daring escape with five empty Spanish ships. They race toward England, prize money and glory beckoning. Just as they draw near, they spot the Venus again. Meanwhile, Poop-Decker, Sally, and Walter work beneath decks to treat Fearless’s infected leg as a fire sweeps across the deck, igniting a blaze that triggers the Venus’s cannons. The fire destroys the Spanish vessels, and Howett’s plan collapses in spectacular fashion.
The rescued crew return to the Admiralty as heroes. Fearless, now with a peg leg, is promoted to Admiral and given a desk job. Poop-Decker and Walter Sweetly are named honorary Captains with pensions, but the young officer reveals his intention to leave the service to marry Sally. The voyage ends on a hopeful note, with the promise of domestic bliss for Poop-Decker and Sally amid the sea’s lingering splendor, a testament to loyalty, cunning, and the stubborn, sometimes comic, courage that drives them forward.
