" When dusk at last comes it comes from the corners, where it’s been waiting all day and seeps through Slough House the way ink seeps through water; first casting tendrils, then becoming smoky black cloud and at last being everywhere, the way it always wants to be. Its older brother night has broader footfall, louder voice, but dusk is the family sneak, a hoarder of secrets. In each of the offices it prowls by the walls, licking the skirting boards, testing the pipes and out on the landings it fondles doorknobs, slips through keyholes, and is content. It leans hard against the front door – which never opens, never closes –and pushes softly on the back, which james in all weathers; it presses down on every stair at once, making none of them creak, and peers through both sides of each window. In locked drawers it hunts for its infant siblings, and with everyone it finds it grows a little darker. Dusk is a temporary creature, and always has been. The faster it feeds, the sooner it yields to the night. "

― Mick Herron , London Rules (Slough House, #5)