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.

"Tell your story," said the man in plain clothes, addressing the latter.

"I am a coachman, Excellency," the man answered in a servile tone. "I have a cab, number eight hundred and seventy-six, at the service of your Excellency, and it was I who drove the gentleman to the hospital yesterday afternoon."

"What gentleman?"

"The gentleman who was hurt in the house of your Excellency."

Volterra stared from the cabman to the man in plain clothes, not understanding. Then it occurred to him that the man in uniform might be wearing it as a disguise, and that he had to do with a party of clever thieves, and he felt for a little revolver which he always carried about with him.

"I know nothing about the matter," he said.

"Excellency," continued the cabman, "the poor gentleman was lying here, close to the door, bleeding from his head. You see the porter has washed the stones this morning."

"Go on." Volterra listened attentively.

"A big man who looked more like a workman than a servant came to call me in the square. When we got here, he unlocked the door himself, and made me help him to put the gentleman into the cab. It was about half- past five or a quarter to six, Excellency, and I waited at the hospital door till eight o'clock, but could not get any money."

"What became of the big man who called you?" asked Volterra. "Why did he not pay you?"

"He was arrested, Excellency."

"Arrested? Why? For taking a wounded man to the hospital?"

"Yes. You can imagine that I did not wish to be concerned in other people's troubles, Excellency, nor to be asked questions. So when I had seen the man and the doorkeepers take the gentleman in, I drove on about twenty paces, and waited for the man to come out. But soon two policemen came and went in, and came out again a few minutes later with the big man walking quietly between them, and they went off in the other direction, so that he did not even notice me."

"What did you do then?"

"May it please your Excellency, I went back to the door and asked the doorkeeper why the man had been arrested, and told him I had not been paid. But he laughed in my face, and advised me to go to the police for my fare, since the police had taken the man away. And I asked him many questions but he drove me away with several evil words."

"Is that all that happened?" asked Volterra. "Do you know nothing more?"

"Nothing, your Excellency," whined the man, "and I am a poor father of a family with eight children, and my wife is ill--"

"Yes," interrupted Volterra, "I suppose so. And what do you know about it all?" he enquired, turning to the man in plain clothes.

"This, sir. The gentleman was still unconscious this morning, but turns out to be a certain Signor Pompeo Sassi. His cards were in his pocket-book. The man who took him to the hospital was arrested because he entirely declined to give his name, or to explain what had happened, or where he had found the wounded gentleman. Of course all the police stations were informed during the night, as the affair seemed mysterious, and when this cabman came this morning and lodged a complaint of not having been paid for a fare from this palace to the hospital, it looked as if whatever had happened, must have happened here, or near here, and I was sent to make enquiries."

"That is perfectly clear," the Baron said, taking out his pocket-book.

"You have no complaint to make, except that you were not paid," he continued, speaking to the cabman. "There are ten francs, which is much more than is owing to you. Give me your number."

The man knew that it was useless to ask for more, and as he produced his printed number and gave it, he implored the most complicated benedictions, even to miracles, including a thousand years of life and everlasting salvation afterwards, all for the Baron, his family, and his descendants.

"I suppose he may go now," Volterra said to the police officer.

The cabman would have liked to stay, but one of the soldiers opened the postern and stood waiting by it till he had gone out, and closed it upon his parting volley of blessings. The Senator reflected that they might mean a vote, some day, and did not regret his ten francs.

"I know Signor Sassi," he said to the detective. "He was the agent of Prince Conti's estate, and of this palace. But I did not know that he had been here yesterday afternoon. I live in the Via Ludovisi and had just come here on business, when you knocked."

He was very affable now, and explained the porter's absence, and the fact that a gentleman who had lived in the house, but had left it, had accidentally taken his key with him, so that it was necessary to get a workman to open the door.

"And it is as well that you should be here," he added, "for the big man of whom the cabman spoke may be the servant of that gentleman. I remember seeing him once, and I noticed that he was unusually big. He may have been here yesterday after his master left, and we may find some clue in the apartment."

"Excellent!" said the detective, rubbing his hands.

He was particularly fond of cases in which doors had to be opened by force, and understood that part of his business thoroughly.

The key turned in the lock of the postern, and the porter entered, bringing Gigi with him. They both started and turned pale when they saw the policeman and the detective.

"At what time did Signor Malipieri send you out on that errand yesterday afternoon?" asked Volterra, looking hard at the porter.

The old man drew himself up, wiped his forehead with a blue cotton handkerchief, and looked from the Baron to the detective, trying to make out whether his employer wished him to speak the truth. A moment's reflection told him that he had better do so, as the visit of the police must be connected with the stain of blood he had washed from the pavement, and he could prove that he had nothing to do with it.

"It was about five o'clock," he answered quietly.

"And when did you come back?" enquired the detective.

"It was dusk. It was after Ave Maria, for I heard the bells ringing before I got here."

"And you did not notice the blood on the stones when you came in, because it was dusk, I suppose," said the detective, assuming a knowing smile, as if he had caught the man.

"I saw it this morning," answered the porter without hesitation, "and I washed it away."

"You should have called the police," said the other severely.

"Should I, sir?" The porter affected great politeness all at once.

"You will excuse my ignorance."

"We are wasting time," Volterra said to the detective. "The porter knows nothing about it. Let us go upstairs."

He led the way, and the others followed, including Gigi, who carried a leathern bag containing a few tools.

"It is of no use to ring again," observed Volterra. "There cannot be anybody in the apartment, and this is my own house. Open that door for us, my man, and do as little damage as you can."