Having been recently betrayed by his last crew member, Jack finds himself all alone on perhaps the most dangerous quest of his young life. Jack is on a mission to find something he isn't even sure exists - the mythical Trident of Poseidon. But there's a band of pirates who are also looking for the treasure. Will they, or Jack, find it first?
After buying a new boat with the gold Teague gave him at the end of his last adventure, Jack sets off to find the legendary Poseidon's Peak and its fabled treasure: the extremely powerful Trident of Poseidon. After several days' journey he finds himself on a deserted island and runs into a young sailer who had been wounded so badly he badly couldn't even remember who he was. Following a restless night of sleep, the boy finally recalls that his name is Bill, and the two decide to journey inland to try and find any clues as to where Poseidon's Peak might be. The two are quickly captured by island natives, however, and Bill discovers that he is somehow able to translate exactly what they're saying. The boys learn that the natives have decided to challenge them to a fight to the death, which Jack naturally cheats at to ensure their survival. The boys then unexpectedly run into none other than Jack's former crewmate Jean Magliore's sister-turned-cat, Constance, whom the natives revere as a deity.
Following their escape from the natives, Jack formulates a plan to get off the island and suggests that they gather logs scattered throughout the beach together to make a raft. During his and Bill's search for suitable wood, they unexpectly discover a strange chariot completely covered in various aquatic life. Upon boarding the chariot, the magical vehicle carries them far out to sea, and just as its about to submerge them beneath the depths of the ocean, the two boys jump off onto a solitary rock in the middle of the water. An immensely frustrated Jack takes his rage out on Constance by flinging her off of the rock, which causes her to lead him and Bill to a mysterious underwater cavern. Constance proceeds to guide them through the seemingly never-ending tunnels, where the two surprisingly come across the crews of The Barnacle and La Fleur de la Mort. Upon seeing Arabella and her fellow crewmates from the Fleur, Bill fully regains his memory as he recalls being rescued by Captain Smith's ship shortly before arriving on the island. It is also revealed that Bill and Arabella established a relationship during this time when she runs up and kisses him (to Jack's annoyance). The happy reunion is quickly interupted, however, when a group of purple-tailed mermaids the likes of which Jack had never encountered before suddenly arrive on the scene. The mermaids reveal themselves to be something of "royalty" among their kind, and request the pirates to keep and protect two items that once belonged to Poseidon himself on their behalf: the magical chariot, and the one thing Jack had been searching for to begin with, the legendary trident. The mermaids explain it is necessary for these items to remain out of the hands of Davy Jones, as he would use them to keep their kind enslaved under his tyrannical control. Soon after however, a different danger arrives riding the chariot and carrying the trident: none other than Jack's arch nemesis, Captain Torrents.
- Jack Sparrow
- William "Bootstrap Bill" Turner
- Arabella Smith
- Laura Smith
- Jean Magliore
- Poseidon (First mentioned)
- British Royal Navy (Mentioned only)
- Trident of Poseidon (First appearance)