The third instalment of the Carnacki Continuum. After a night of shocks and surprises, the Jessop sisters call in the professionals - the discredited inventor Sir Barnard Buxton and Lorne's friend from the Psycho-Analytic Society, the enigmatic Dr John. They set out to hunt down the inter-dimensional creatures which have passed through the portal - only to lose the bizarre creature who calls himself Sigil along the way. They find him, eventually, in the abandoned underground station in King William Street. They find more - much more - than they bargained for.