Helen got up jerkily. "You don't believe all he's told you! It isn't true! I swear it isn't!"
"No, I only believe that your husband was in Oxford yesterday evening, Mrs. North. But I think you had better not swear to anything more. You have already done your best to obstruct the course of justice, which is quite a serious offence, you know. As for you, Mr. North, I'm afraid your account of the murder of Fletcher doesn't fit the facts. If I am to believe that you killed him, I must also believe the story your wife told me at the police station on the day I first interviewed you both. Your wife did leave Greystones by way of the front drive just after ten o'clock, for she was seen. That means that you murdered F'letcher, cleaned the poker with such scrupulous care as to defy even the microscope, and reached the side gate all within the space of one minute. I sympathise with the motive that prompted you to concoct your fairy story, but I must request you to stop trying to hinder me."
"What, didn't he do it after all?" said Neville. "You don't mean to tell me we're right back at the beginning again? How inartistic! How tedious! I can't go on being interested; it's time we reached a thrilling climax."
"There's a catch in it somewhere, and I can't spot it,"
said Sally, frowning at Hannasyde. "What makes you so sure my brother-in-law's innocent?"
"The fact that he was not in London last night, Miss Drew."
Helen put out a wavering hand and grasped a chairback. "He didn't do it?" she said, as though she hardly understood. "Are you trying to trick me into saying something - something -'
"No," Hannasyde replied. "When Mr. North has told me just where he really was on the evening of the 17th I shall be satisfied that neither of you murdered Ernest Fletcher. You, at least, could never have done so."
She gave a queer little sigh, and crumpled up in a dead faint.
"Oh, damn you, Superintendent!" exclaimed Sally, and went quickly forward.