a story about a demon 'in the guise of' an angel [=a demon disguised as an angel; a demon made to look like an angel]
She swindles people 'under the guise of' friendship. [=by pretending to be their friend]
They serve the same basic dish in various 'guises'. [='forms']
(..) and said: "Demon, you will not cross!" But the demon is wicked, full of treachery. Yet again he comes to tempt us in the guise of an innocent. To rid the world of this demon... ...we must burn this child! That's not gonna happen! Mommy! It's okay, baby. (..)2006 Silent Hill