The plan Stephano, Trinculo and (mostly) Caliban formulate is to wait for Prospero to take his afternoon sleep, then steal his magic books so he cannot fight back.
Stephano is then to marry Miranda and become king of the island, and he promises to appoint Trinculo and Caliban as Viceroys[REF] Their plan is foiled, and their vanity exposed, when flashy clothes are left out as a trap by Prospero's loyal servant Ariel.