What plan does Westley come up with in order to rescue Buttercup?

Westley devises a clever plan to rescue Buttercup by first disguising himself as the Dread Pirate Roberts, a feared figure in the sea. He gathers a small crew and employs cunning tactics, including outsmarting the henchmen of Prince Humperdinck, who has taken Buttercup. By leveraging his wit and skills, Westley aims to infiltrate the castle and save her from her impending fate. Overall, his plan relies on both deception and bravery to reunite with Buttercup.