...it's never trust children that look angelic, wear white and hold hands and walk in step.
Just a hint.
Sorry for freaking y'all out. I finally watched the BBC adaptation of Henry James' The Turn of the Screw and am sufficiently freaked out.
Here she is kicking ass as Susan Sto Helit in Hogfather. That's Death granddaughter in the Terry Pratchett universe, in case you didn't know.