“You say that you rang several times at Signor Malipieri’s door,” he said.  “Has he not told you that he is going to live somewhere else?”

“No, sir.”

“Does he never leave his key with you when he goes out?”

“No, sir.”

“Did you see him come in last night?  Was he at home?”

“No, sir.  I rang several times, about dusk, but no one opened.  I did not hear him come in after that.  Shall I go up and ring again?”

“No.”  Volterra reflected for a moment.  “He has left, and has taken his key by mistake,” he said.  “But I should think that you must have seen him go.  He would have had some luggage with him.”

The porter explained that Malipieri had sent him on an errand on the previous afternoon, and had been gone when he returned.  This seemed suspicious to Volterra, as indeed it must have looked to any one.  Considering his views of mankind generally, it was not surprising if he thought that Malipieri might have absconded with something valuable which he had found in the vaults.  He remembered, too, that Malipieri had been unwilling to let him visit the treasure on the previous day, and had named the coming afternoon instead.

“Can you get a man to open the door?” he asked.

“There is Gigi, the carpenter of the palace,” answered the porter.  “He is better than a locksmith and his shop is close by—­but there is the water in the cellars—­”

“Go and get him,” said the Baron.  “I will wait here.”

The porter went out, and Volterra began to walk slowly up and down under the archway, breathing the morning air with satisfaction, and jingling a little bunch of keys in his pocket.

There was a knock at the postern.  He listened and stood still.  He knew that the porter had the key, for he had just seen him return it to his pocket after they had both come in; he did not wish to be disturbed by any one else just then, so he neither answered nor moved.  The knock was repeated, louder than before.  It had an authoritative sound, and no one but Malipieri himself would have a right to knock in that way.  Volterra went to the door at once, but did not open it.

“Who is there?” he asked, through the heavy panel.

“The police,” came the answer, short and sharp.  “Open at once.”

Volterra opened, and was confronted by a man in plain clothes, who was accompanied by two soldiers in grey uniforms, and another man, who looked like a cabman.  On seeing a gentleman, the detective, who had been about to enter unceremoniously, checked himself and raised his hat, with an apology.  Volterra stepped back.

“Come in,” he said, “and tell me what your business is.  I am the owner of this palace, at present.  I am Baron Volterra, and a Senator.”

The men all became very polite at once, and entered rather sheepishly.  The cabman came in last, and Volterra shut the door.

“Who is this individual?” he asked, looking at the cabman.