There must have been an encounter between Barrimore and Miss Cost. He had seen Emily pass and repass, had come out of concealment and gone to the enclosure. By that time Miss Cost was approaching. Why, when he saw her, should he again take cover, and where? No: they must have met. What, then, did they say to each other in the pouring rain? Did she tell him she was going to retrieve the necklace? Or did he, having seen her approaching, let himself into the enclosure and hide behind the boulder? But why? And where, all this time, was Wally? Dr Maine and Miss Emily had both seen him, soon after half past seven. He had shouted at Miss Emily and then ducked out of sight. The whole damned case seemed to be littered with people that continually dodged in and out of concealment. What about Trehern? Out and about in the landscape with the rest of them? Inciting his son to throw rocks at a supposed Miss Emily? Dr Maine had not noticed him but that proved nothing.

Next, and he faced this conundrum with distaste, what about Mrs Barrimore alias the Green Lady? Did she fit in anywhere or had he merely stumbled down an odd, irrelevant by-way? But why was she so frightened at the thought of her husband being told of her masquerade? The Green Lady episode had brought Barrimore nothing but material gain. Wouldn’t he simply have ordered her to shut up about it and if anything, relished the whole story? She had seemed to suggest that the fact of Alleyn himself being aware of it would be the infuriating factor. And why had she been so distressed when she was alone in the garden? At that stage there was no question of her identity with the Green Lady being discovered.

Finally, of course, was Miss Cost murdered, as it were, in her own person, or because she was mistaken for Miss Emily?

The answer to that one must depend largely upon motive and motive is one of the secondary elements in police investigation. The old tag jog-trotted through his mind. ‘Quis? Quid? Ubi? Quibus auxilis? Cur? Quomodo? Quando?’ Which might be rendered: ‘Who did the deed? What was it? Where was it done? With what? Why was it done? And how done? When was it done?’ The lot!

He completed his notes and read them through. The times were pretty well established. The weapon. The method. The state of the body. The place – no measurements yet, beyond the rough ones he and Coombe had made on the spot. Bailey would attend to all that. The place? He had described it in detail. The boulder? – between the boulder and the hill behind it, was a little depression, screened by bracken and soft with grass. A ‘good spot for courting couples,’ as Coombes had remarked, ‘when it wasn’t raining.’ The ledge –