“Anyone could see that the fourth man was a dark horse. He might be the murderer whom they were shielding, possibly. But there was another explanation of his disappearance; he might be someone well known to the local people, and whom it was desirable to keep under cover. How would that fit in with things? Suppose the claimant was an impostor; he wouldn't be very anxious to meet the villagers more than he could help, for fear of dropping on someone who might trap him and expose him. The less he saw of his neighbors the better; and his disfigurement gave him a fair excuse for keeping indoors in the daytime. Staveley was well enough known to the villagers also; and perhaps he had good reason for not wishing his presence known. If the fourth man was in the same boat, then none of them would care to go shopping and so forth, and yet supplies had to be got daily. Hence it might be convenient to have a man like Billingford as the nominal host, to act as go-between for them in their public transactions. That's how it appeared to me. Naturally, I was curious about the fourth man, and I got you, inspector, to set a watch and see if he could be recognised. “That left me with a fair suspicion that these fellows were hatching some devilment or other at the cottage. Then I noticed the card-index; and I saw light to some extent. A card-index implies the need for ready reference. The claimant, if he were a fraud, would need to cram himself with all the available facts about the doings of the real Derek Fordingbridge—just as Arthur Orton crammed up all the facts about Roger Tichborne. And a card-index would be the handiest repository of all the news they could collect. As you saw for yourself, squire, that guess of mine was right. “Assume that state of affairs—I had no certain knowledge then—and things begin to fall into their places. I've given you my notion of why Billingford was needed. What about the other three? “The claimant was obviously needed to represent Derek Fordingbridge; and he'd been cast for the part on two grounds. First, his face was so much damaged that no one could swear to his original appearance. He might quite well have been Derek or anyone else, so far as that went. Then the loss of his fingers made him invaluable also, because he couldn't be expected to write like the real Derek nowadays, with a mutilated hand. All that was wanted in addition was a good memory to cram up the immense amount of facts that they needed in order to meet questioning. “Then there was Staveley. What was he doing in the affair? Well, obviously, he had a lot of information about the Foxhills people which he must have picked up while he stayed there with the real Derek on leave, and also some more facts which he must have learned from Mrs. Fleetwood from time to time.