The Prisoner in the Opal by A.E.W. Mason — Read

Mr. Ricardo sat on the edge of his bed with his head in his hands, whilst his servant packed. His head was in a whirl. All that he had seen and heard that day was jumbled together in his mind -- the footprints, the mask, the guttered candle, the tumbled bed, the picture of the Grand Canal which meant nothing at all, the Abbé and his casuistries -- oh, and Joyce Whipple's bracelet -- yes, and Hanaud's astonishing declaration that the murderers of Evelyn Devenish dare not repeat their crime -- and what Hanaud had seen in Diana Tasborough's bedroom and he hadn't -- and what Hanaud had deduced from the books at Robin Webster's bedside, and he hadn't -- and Robin Webster's stark, appalling fury on the terrace. His head ached as he enumerated his bewilderments, and he felt very grateful to Hanaud for providing him with so convenient an exit from this tragic house. He would have time in Bordeaux to take out his tables and reduce -- if it was only his ignorance -- to some sort of order. He would also be relieved of the dislike for him which Diana so obviously felt. Accordingly he lit a cigarette and tried to banish the whole tangle from his thoughts.

But he couldn't do it. For his memory began to stir. He sat up erect and gasped. Elias Thomson looked up from his portmanteaux and saw his employer staring into vacancy with an open mouth.