They followed him, and he pointed to a framework of carved wood that connected the four posts.

“What is this on the frieze running above the capitals of the little Ionic pillars?”

“The papal crown and keys,” said Mary.

“Good!  Now regard the other side.”

“A coat of arms—­a golden bull on a red ground—­why, father, that was what puzzled you at Florence!”

“Surely it was.  The thing stuck in my memory, yet I could not remember where I had seen it before.”

Signor Mannetti prepared for his effect, then made it.

“The arms of the Borgia!  The arms of the Spanish Pope, Alexander VI. of unholy memory.  So all is told, and we will soon go to bed.  Having marked them this morning, you will see how readily I was led into the heart of the secret.  It only needed some such certain sign.  And everything that had happened was consonant with this explanation.  The first to suffer puzzled me; but I solved that problem, too.  You shall hear how each woman and each man was slain.  Look at this mattress upholstered in satin—­ there lies the unsleeping thing that brings sleep so quickly to others!  I guessed it this morning; I proved it to-night.  At seventeen minutes past eight Prince was dead; but not until I awoke, near two o’clock, did I dare approach him.  For how did he die?  The moment the heat of his ancient body penetrated the mattress under him, it released its awful venom.  He stretched himself, curled up again, and, as the exhalation rose, with scarcely a tremor he passed from sleep into death.  Needless to tell you that I kept far from him, for I guessed that not until the poor fellow was cold would the demon in the mattress sink down and disappear, as the effret into his bottle.  Then mattress and dog were alike harmless, as they are now.  I gave him only five hours, for he was a small, thin beast, and the heat soon left his body.”

“But, signor—­”

“I shall anticipate all your objections if you will listen a little longer, dear Mrs. May.  Let us sit again, and question me after I have spoken, if any doubts remain unanswered.  Another liqueur, Masters.”

He sipped, and preserved silence for a few moments, while none spoke.  Then from his armchair he traversed the story of the Grey Room, and proved amazingly familiar with the smallest detail of it.  Indeed, when at last he had finished, none could find any questions to ask.  “There are two very interesting preliminary facts to note, my friends,” began the signor.  He beamed upon them, and enjoyed his own exposition with unconcealed gusto.  “The first is that a room, already suffering from sinister traditions, and held to be haunted, should have been precisely that into which this infernal engine of destruction was introduced.  Yet what more natural?  You have the furniture, and, for the time being, do not know what to do with it.  The house is already full of beautiful things, and these surplus treasures you store here, to be safe and out of the way, in a room which is not put to its proper use.  You are not collectors or experts.  Sir Walter’s father did not share his father’s enthusiasm, neither did Sir Walter care for old furniture.  So the pieces take their place in this room, and are, more or less, forgotten.