Who, he had asked himself the night before—who, of all the persons who figured on the list Joan and he had compiled, was most likely to have done the thing? He felt certain that it was not the work of a stranger: the whole of the circumstances seemed to point to some one familiar with the house and its ways. Yet, on the evidence, it seemed clear enough that no one among those they had put upon their list could be guilty. But their list included everybody. Very well—this had been his first inspiration—there must be something wrong with the evidence. It must point away from the guilty, as it had pointed towards the innocent. The murderer who had laid that clever trail to incriminate Walter Brooklyn would obviously have taken the precaution to lay a trail pointing away from himself. Indeed, whoever had the apparently clearest alibi was on this showing the most likely to be guilty. It would be safest, in the circumstances, to ignore for the moment all the evidence which seemed to prove innocence, and simply consider, in the light of the remaining conditions, who was most likely to have been the murderer.

This narrowed the field considerably. The women, except as possible accessories, could be ruled out of account in any case; for no woman could have struck the blows by which the two cousins had met their deaths. That left—whom? Walter Brooklyn was out of it; for his alibi had been not merely accepted, but tested beyond possible doubt. Ellery could hardly suspect himself, though he admitted that any one else, following out his line of thought, might still suspect him. His alibi was not conclusive: it depended on the word of one man. But he could rule himself out: he could say positively that he had not done the thing. Then who remained? Only Harry Lucas, Carter Woodman, and the two servants, Winter and Morgan. Among these, if he was right, the real murderer must be found.

It was ludicrous, Ellery felt, to suspect his guardian. Harry Lucas had no possible motive, and he was the very last man for such a deed. He was ruled out of consideration as soon as the thought was conceived. About Winter and Morgan Ellery could not feel the same full certainty; but he was very strongly of opinion that the murders were not the work of a servant, and that neither of these men had the qualities which the deed seemed to demand.

Then there was left only—Carter Woodman. It was on that thought that Ellery had fallen asleep, and that was the idea that now came back to him with added certainty. Carter Woodman was the murderer.

But was not the whole idea preposterous? Woodman not merely had an alibi which had satisfied the police; he was a relative, an old personal friend, the tried and trusted business adviser of the Brooklyns. His wife was one of Joan’s dearest friends, and he himself had been constantly about with the men of whose murder Ellery was now suspecting him. The idea seemed preposterous enough, when it was put in that way; but, though Ellery presented these difficulties to his mind in all their strength, they did not at all change his attitude. No one else was the murderer: therefore Carter Woodman was.

There entered, certainly, into Ellery’s conviction his own strong dislike of Woodman. The suggestion of Woodman’s guilt, once made, was plausible to him, because he had not at all the feeling that the deed was incongruous. It would have been utterly incongruous with what he knew of any other possible suspect, even Walter Brooklyn; but the cap seemed to fit Carter Woodman. Ellery said to himself that Woodman was just the sort of chap who would commit murder, if he had a strong enough motive.

Yes; but where was the motive in this case? What did Woodman stand to gain? Knowing the terms of the will, Ellery was aware that he gained nothing directly; for Sir Vernon’s fortune would now pass mainly to Walter Brooklyn, and the rest to Joan and to Marian Brooklyn. Of course, Woodman might hope to get Sir Vernon to make a new will in his favour, and, in any case, he probably stood now a fine chance of becoming the managing director of the Brooklyn Corporation. But a man would hardly commit two desperate murders merely on such chances. The more Ellery considered the matter, the surer he felt that there must be something else behind—something of which he was unaware, that would make the whole case plain.

He must see Joan, and tell her what he suspected. She might well know some fact, of which he was ignorant, that would throw a clear light on the motive behind the crimes. But would she ever believe that Woodman had done it? Ellery realized that what to him seemed like certainty would seem to others only a guess, and that he had not merely no proof but actually no evidence to support his assumptions. What evidence there was told the other way. Still, this did not shake his assurance. He must make Joan see the case as he had come to see it. Then they could seek together for the proof.

As soon as Ellery had breakfasted, he set off for Liskeard House to find Joan. They must get to work at once.

Joan, too, had spent a good part of the night thinking; but her thoughts had brought her no nearer to a solution of the mystery surrounding the murders. There was literally not one, of all those who seemed to be concerned, who could, in her judgment, have been the murderer. She was reduced to the supposition that it must be some outsider—some one whom they had not even dreamed so far of connecting with the crimes.