The thing, whatever it was - and no one was ever sure afterward whether it was a dream or a fit or what - happened at that peculiar hour before dawn when human vitality is at its lowest ebb. The Blue Hour they sometimes call it, l'here blue - the ribbon of darkness between the false dawn and the true, always blacker than all the rest of the night has been before it. Criminals break down and confess at that hour; suicides nerve themselves for their attempts; mists swirl in the sky; and - according to the old books of the monks and the hermits - strange, unholy shapes brood over the sleeping rooftops. At any rate, it was at this hour that her screams shattered the stillness of that top-floor apartment overlooking the Pare Conceal. Curdling, razor-edged screams that slashed through the thick bedroom door. ("I'm Dangerous Tonight")

The Fantastic Stories of Cornell Woolrich