A grandfather lovingly reads a captivating tale to his ill grandson, who initially finds the story uninteresting. The narrative revolves around Buttercup, a beautiful young woman living in the imaginary kingdom of Florin. When she gives orders to her farmhand Westley, he always responds with, "As you wish." Their romance blossoms, but Westley departs to seek his fortune, only to be presumed dead when his ship is attacked by the feared Dread Pirate Roberts.
Five years later, Buttercup is compelled to marry Prince Humperdinck, but before the nuptials, she is abducted by a trio of criminals: the cunning Sicilian Vizzini, the towering giant Fezzik, and the skilled swordsman Inigo Montoya, who is on a quest for vengeance against a six-fingered man who killed his father. They escape, but are pursued by a mysterious man in black, leading to thrilling encounters with the prince's soldiers.
On the perilous Cliffs of Insanity, the man in black confronts Inigo, defeating him in a fierce duel before overpowering Fezzik and cunningly tricking Vizzini into drinking poison. While carrying off Buttercup, she deduces his identity as the Dread Pirate Roberts and accuses him of killing Westley, pushing him into a gorge. As he falls, he exclaims, "As you wish!" This revelation prompts Buttercup to leap after him, leading to their emotional reunion.
Navigating through the treacherous Fire Swamp to evade capture, Westley reveals to Buttercup that the title of Dread Pirate Roberts can be passed down from one pirate to another. They plan to retire and hand over the title, but their plans are thwarted when Humperdinck seizes them after their escape from the swamp. Buttercup agrees to return to Humperdinck under the pretense of securing Westley's release, but he secretly orders the sinister Count Rugen to imprison Westley in his torture chamber known as the Pit of Despair.
As tensions rise, Buttercup threatens to take her own life if the wedding proceeds, prompting Humperdinck to deceitfully promise to find Westley for her. The prince schemes to instigate a war with Guilder by assassinating Buttercup and blaming the neighboring country. Meanwhile, Fezzik, now part of the brute squad, encounters a drunken Inigo, whom he helps to regain sobriety. They resolve to rescue Westley from the clutches of the malevolent Rugen.
Upon recognizing Humperdinck's cowardice for not actively seeking Westley, Buttercup is imprisoned while Humperdinck tortures Westley into a state resembling death. Following a series of adventurous events, Inigo and Fezzik locate Westley’s lifeless form and bring him to Miracle Max, a local healer, who manages to revive him despite his weakened condition.
As Westley, Inigo, and Fezzik launch an audacious assault on the castle, panic ensues within Humperdinck, who attempts to hasten the wedding. Inigo confronts Rugen, avenging his father's death in a heated battle. Meanwhile, Westley reassures Buttercup that their marriage is invalid as she never completed her vows. When the prince confronts Westley for a duel, Westley stands bravely, scaring him into submission.
Finally, as dawn breaks, Inigo and Fezzik help Westley and Buttercup escape on horseback. Facing uncertain futures, Inigo is offered the title of Dread Pirate Roberts as they ride toward freedom, and the reunited couple shares a passionate kiss. The grandfather’s reading captivates the sick grandson, who eagerly pleads for another story the following day, to which the grandfather fondly replies, "As you wish."
