what causes caliban and the others to turn aside from their plot

Ariel leads them in their drunkenness through a patch of briars and into a filthy bog. Prospero then sets a trap for them; they touch the beautiful clothes they see and are hounded by spirits in the shape of hounds.

Caliban, Stephano, and Trinculo come looking for Prospero, and swipe a few garments of Prospero's on their way. Caliban still wants very much to kill Prospero, and carry out this plot; however, Trinculo and Stephano are very drunk, as usual, and prove completely incapable of anything but petty theft. Prospero catches them‹not difficult, since they are making a huge amount of noise--and sends Ariel after them as they flee.