"But the man Rose?" I insisted.
"An excellent part, alternately played with remarkable skill by the Captain and his female accomplice."
"Do reconstruct the whole thing for me," I pleaded. "I own that I am bewildered."
And from my bag I extracted a brand-new piece of string which I handed to him with an engaging smile. Nothing could have pleased the fatuous creature more. With long, claw-like fingers twiddling the string, he began leisurely:
"Nothing could be more simple. Captain Shillington takes leave of his fiancée, having her pearls in his pocket. It is then about half-past eleven. Henry Buckley has gone to his club, Shillington having appointed to see him at Mexfield House soon after midnight. There is, therefore, plenty of time. Shillington hurries home, changes his personality into that of James Rose, as he often has done before, and subsequently interviews Henry Buckley on the door-step. You can see that, can't you?"
"Easily," I replied.
"Then as soon as he has got rid of Buckley, our friend the Captain quits the personality of a snuffy, middle-aged man-servant, and becomes himself once more. He goes back to the neighbourhood of Mayfair, hails a taxi and drives to Mexfield House. But in the meanwhile the female confederate—we'll call her Miss Shillington for convenience' sake—in male attire and evening dress, wearing a light overcoat, a light-coloured scarf and a white carnation in her button-hole, lounges under a doorway in Somerset Street, waiting to play her part. Now do you see how simple it all is?"
"Perfectly," I admitted. "As you said before, they had provided themselves with a blood-stained hat, which presently they threw into the river, together with the scarf; and what happened after that?"
"They walked home quietly and went to bed."
"What? Both of them? ... But the mother?"