To amplify his and the East India Trading Company's influence in the Caribbean, Lord Cutler Beckett (Tom Hollander) resorts to extreme measures, ruthlessly executing anyone, including innocent women and children, suspected of even the slightest connection to piracy. Now in possession of Davy Jones's heart (Bill Nighy), Beckett commands Jones to annihilate all pirate ships.
Defiant prisoners broke into song, calling forth the nine pirate lords of the (fourth) Brethren Court to gather at Shipwreck Cove and confront Beckett’s tyranny. However, the charismatic Captain Jack Sparrow (Johnny Depp), the acknowledged pirate lord of the Caribbean, finds himself in a bind as he never named a successor and thus must take his rightful place among them.
With a daring plan, Captain Barbossa ([Geoffrey Rush]) assembles a team that includes Will Turner ([Orlando Bloom]), Elizabeth Swann ([Keira Knightley]), Tia Dalma ([Naomie Harris]), and the crew of the Black Pearl to rescue Jack. Their journey takes them to Singapore, where the fierce pirate lord Sao Feng ([Chow Yun-Fat]) holds the coveted map to World's End, the gateway to Davy Jones's Locker, where Jack is imprisoned for eternity.
A tense negotiation unfolds between Elizabeth and Barbossa as they bargain with Feng for both the map and a ship. Tempers flare when Feng realizes Will’s previous attempt to steal from him. In the midst of this chaos, the British Royal Navy, led by Mercer ([David Schofield]), strike unexpectedly, culminating in a battle that sees Will striking a deal with Feng: the Black Pearl in exchange for Jack's freedom.
With their mission leading them through treacherous icy seas, the crew eventually sails over a colossal waterfall into the Locker. Jack, trapped on the Pearl, grapples with hallucinations of a ghostly crew that embodies his various personality traits. Mysterious crab-like creatures, likely sent by Tia Dalma, ferry the Pearl to an ocean shore, allowing Jack to reunite with his former crew, who once sought to end his life.
As Jack contemplates his past choices, Tia Dalma divulges the heart-wrenching tale of Davy Jones, who was cursed by Calypso, the Goddess of the Sea and his lover. Their tragic separation ultimately led him to forfeit his duty and accept a monstrous transformation. The emotional stakes are raised even further for Elizabeth when she encounters the spirit of her father, Governor Weatherby Swann ([Jonathan Pryce]), who reveals that whoever dares to stab Jones's heart becomes the immortal captain of the Flying Dutchman. Fueled by rage and grief, Elizabeth swears revenge on Beckett.
The Black Pearl remains ensnared in the Locker until Jack deciphers a critical clue that suggests they must capsize the ship to escape back to the living world. As the sun sets, their vessel is flipped over, and at dawn's first light, they emerge—marking their return with a dazzling green flash. Stopping on a deserted island to replenish their supplies, they come across the remnants of the Kraken, slain by Jones on Beckett's orders, prompting Jack to recognize the dire threat facing piracy itself.
As they delve deeper into the fray, they find themselves ambushed by Sao Feng, who betrays Will while maintaining a secret deal with Beckett to turn over the entire crew in exchange for the Black Pearl. Sparrow is captured and taken aboard the Endeavor, refusing to divulge the location of the Brethren Court, instead crafting a scheme to mislead Beckett and lure him into a trap.
Events take a dark turn as Feng is double-crossed by Beckett, compelling him to negotiate with Barbossa for Elizabeth’s freedom—believing her to be Calypso reborn. Just as Jones launches an attack on Feng’s ship, the eventual chaos claims Feng's life, leaving Elizabeth to assume command as the newly appointed Pirate Lord of the South China Sea. Captured alongside her crew and Admiral James Norrington ([Jack Davenport]), Elizabeth ultimately escapes with Norrington’s help, but not before tragedy strikes.
In a daring move, Will leads a path of corpses for Beckett’s fleet to follow, employing Jack's enchanted compass to navigate him to Shipwreck Cove. At this pivotal gathering, the nine pirate lords present their nine pieces of eight to discuss the impending war against Beckett. Unable to reach a consensus, Barbossa invokes Captain Teague Sparrow ([Keith Richards]), Jack's father, who confirms only a Pirate King can declare war. In a surprising twist, Elizabeth earns the title of Pirate King, commanding her fellow pirates to prepare for battle against Beckett.
The conflict escalates dramatically as Elizabeth and Barbossa trade Jack for Will, yet Barbossa cunningly manipulates the other lords into surrendering their pieces of eight, necessary to release Calypso from her human constraint. With Will revealing that Jones betrayed Calypso, a furious storm brews, signalling chaos as the British fleet approaches.
In the ensuing melee, Sparrow escapes captivity aboard the Flying Dutchman, where he retrieves the legendary Dead Man's Chest. Jones, bloodied and vengeful, engages Mercer in battle, leading to a climactic duel for the key to the chest which Jack seizes at the final moment. The Black Pearl and the Flying Dutchman face off in the throes of a tumultuous maelstrom, where Will seizes the opportunity to propose to Elizabeth, with Barbossa performing a hasty marriage amidst the pandemonium.
Following Will’s fateful confrontation with Davy Jones, who fatally wounds him, Jack plays a critical role in the fight against Jones. With courage and cunning, Jack aids Will in delivering the fatal stab to Jones's heart, ultimately putting an end to the monstrous pirate's reign. As the mist clears, the Black Pearl and the Flying Dutchman prepare to confront Beckett head-on, leading to the notorious captain’s demise.
Though Will emerges victorious and the crew of the Dutchman reclaim their humanity, he accepts his fate to navigate the seas as their captain. In a bittersweet farewell, Will and Elizabeth share a brief yet tender moment together on an isolated island before he sets sail at sunset, leaving behind the Dead Man's Chest for her to safeguard.
In a twist of fate, Barbossa seizes command of the Black Pearl once more, leaving a stranded Jack and Gibbs in Tortuga. But Jack, always playfully cunning, had pre-emptively secured the map’s core—an essential guide to the Fountain of Youth. The story closes with a poignant post-credits scene set a decade later, featuring Elizabeth and their son atop a cliff as the Flying Dutchman appears over the horizon, symbolizing hope and love that still endures.
