What action does caliban suggest when he discusses killing Prospero stephano and trinculo

Prospero gives his blessing to Ferdinand and Miranda, warning Ferdinand only that ... that his consternation is largely a result of his age; he says that a walk will soothe him ... Ariel tells him of the men's drunken scheme to steal Prospero's book and kill him ... Caliban, Trinculo, and Stephanoenter, wet from the filthy pond.