“Is this a jest?”

“Isaac’s story is that you married her mother, who was his sister, in Paris, nineteen and a half years ago.  Her name was Cecile Ruth Leneveu, and she was acting at one of the theatres.  She was really Isaac’s half-sister.  His father had brought him from Paris when he was only a child, and married again almost at once.  According to his story, Ruth’s mother lived with you for two years—­until, in fact, you went to Chili to take command of the troops there, at the time of the revolution.  When you returned, she was dead.  You were told that she had given birth to a daughter and that she, too, had died.”

“That is true,” Sabatini admitted slowly.  “I came back because of her illness, but I was too late.”

“The child did not die,” Arnold continued.  “She was brought up by Isaac in a small convent near Rouen, where she remained until two years ago, when he was forced to come to England.  He brought her with him as, owing to her accident, she was unable to take the post of teacher for which she had been intended, and the convent where she was living was unexpectedly broken up.  Since then she has lived a sad life with him in London.  His has been simply a hand-to-mouth existence.”

“But I do not understand why I was kept in ignorance,” Sabatini declared.  “Why did he not appeal to me for help?  Why was my daughter’s existence kept a secret from me?”

“Because Isaac is half a fanatic and half a madman,” Arnold replied.  “You represent to him the class he loathes, the class he has hated all his life, and against which he has waged ceaseless war.  He hated your marriage to his sister, and his feelings were the more embittered because it suited you to keep it private.  He has nursed a bitter feeling against you all his life for this reason.”

Sabatini turned stiffly away.  He walked to the window, standing for a moment or two with his back to Arnold, looking out into the quiet street.  Then he came back.

“I must go to this man at once,” he said.  “You can take me there?”

“I can take you,” Arnold assented, doubtfully, “and I have even a message from him asking you to visit him, but I warn you that he is in a dangerous mood.  I found him the solitary occupant of a miserable room in the back street of a quarter of London which reminded me more than anything else of some foreign city.  He has cleared the furniture from the room, reared a table up on end, and is crouching behind it with a Mauser pistol in his hand and a box of cartridges by his side.  My own belief is that he is insane.”

“It is of no account, that,” Sabatini declared.  “One moment.”

He touched the bell for his servant, who entered almost immediately.

“You will take a cab to 17, Grosvenor Square, Pietro,” he directed.  “Present my compliments to the lady of the house, and tell her that an occurrence of the deepest importance deprives me of the honor of dining to-night.”