Lady Warren spoke with the ring of authority. She was not guessing blindly; sheknew something—but not enough. It was this half-knowledge which terrified Helen. Had any of Dr. Parry’s audience told her about the murder she would naturally have heard, also, about the discovery of the body in Captain Bean’s garden.. Nurse Barker, alone, stood outside the circle of informed listeners. That fact did not necessarily assume the most sinister significance. To use the Professor’s phrase, her alibi was established. When Ceridwen was being done to death, she was bumping, in the old car, towards the Summit, in Oates’ company. Yet—if she had told her patient—she must have possessed some horrible specialized knowledge of the movements, or intentions of the maniac—which stopped short with the commission of the murder. As Lady Warren gripped her wrist, Helen realized. that it was useless to lie. “How do you know?” she asked. The old woman did not reply. She gave a hoarse gasp. “Ah!
