"Nonsense. Why should your aunt ‘cross Faith off’? Why should she refuse to have Miss Usher in her house? Granting that there were many possible explanations, there was one suggested by the known facts: that she would not receive as a guest the natural daughter of her former husband. And I had just learned that Faith Usher was Albert Grantham’s natural daughter, and that you were aware of it. So I had the implication, and I arranged to test it. If Mrs Robilotti, suddenly confronted by Faith Usher’s mother extending a friendly hand, took the hand and betrayed no reluctance, the implication would be discredited. I expected her to shrink from it, and I was wrong. I may learn some day that what a woman will do is beyond conjecture. Instead of shrinking, she struck. I repeat, Mrs Usher, I regret it. I did not foresee it."
"You can’t have it both ways," Byne said. "You say my aunt wouldn’t have Faith Usher in her house because she knew she was her former husband’s natural daughter. But she did have her in her house. She knew she had been invited, and she let her come."
Wolfe nodded. "I know. That’s the point. That’s my main reason for assuming that your aunt killed her. There are other-"
"Hold it," Cramer snapped. His head turned. "Mrs Robilotti, I want you to know that this is as shocking to me as it is to you."
Her pale grey eyes were on Wolfe and she didn’t move them. "I doubt it," she said. "I didn’t know any man could go as low as this. This is incredible."
"I agree," Wolfe told her. "Murder is always incredible. I have now committed myself, madam, before witnesses, and if I am wrong I shall be at your mercy. I wouldn’t like that. Mr Cramer. You are shocked. I can expound, or you can attack. Which do you prefer?"
"Neither one." Cramer’s fists were on his knees. "I just want to know. What evidence have you that Faith Usher was Albert Grantham’s daughter?"