When Inspector French felt really up against it in the conduct of a case, it was his invariable habit to recount the circumstances in the fullest detail to his wife. She, poor woman, haled from the mysterious household employments in which her soul delighted, would resignedly fetch her sewing and sit placidly in the corner of the Chesterfield while her lord and master strode up and down the room stating his premises, arguing therefrom with ruthless logic and not a few gestures, sifting his facts, grouping them, restating them. . . . Sometimes she interjected a remark, sometimes she didn’t; usually she warned him to be careful not to knock over the small table beside the piano, and invariably she wished he would walk on the less worn parts of the carpet. But she listened to what he said, and occasionally expressed an opinion, or, as he called it, “took a notion.” And more than once it had happened that these notions had thrown quite a new light on the point at issue, a light which in at least two cases had indicated the line of research which had eventually cleared up the mystery.

On the second evening after his return from Spain, the Inspector was regaling her with a by no means brief résumé of the Hatton Garden crime. She had listened more carefully than usual, and presently he found she had taken a notion.

“I don’t believe that poor old man was out to do anything wrong,” she declared. “It’s a shame for you to try to take away his character now he’s dead.”

French, stopping his pacing of the room, faced round.

“But I’m not trying to take away his character, Emily dear,” he protested, nettled by this unexpected attack in the rear. “I’m only saying that he’s the only person we know of who could have got an impression of the key. If so, it surely follows he was out to rob the safe.”

“Well, I believe you’re wrong,” the lady affirmed, continuing with a logic as relentless as his own, “because if he was out to rob the safe, he wasn’t the sort of man that you described, and if he was the sort of man that you described, why, then, he wasn’t out to rob the safe. That’s what I think about it.”

French was a trifle staggered. The difficulty he had recognised from the beginning, but he had not considered it serious. Now, put to him in the downright, uncompromising language in which his wife usually clothed her thoughts, it suddenly seemed to him overwhelming. What she said was true. There was here a discrepancy. If Gething really bore the character he was given by all who had known him, he was not a thief.

He ceased his restless movement, and sitting down at the table, he opened his notebook and began to look up what he had actually learned about the dead man. And the more he did so, the more he came to believe that his wife was right. Unless all this cloud of witnesses were surprisingly mistaken, Gething was innocent.

His mind reverted to the other horn of the dilemma. If Gething were innocent, who took the impression of the key? It was not obtained from that in the bank, therefore it was copied from that in Mr. Duke’s possession. Who had done it?

No one at the office, at least not unless Mr. Duke was greatly mistaken. And he did not believe the principal could be mistaken on such a point. The breaking through of his regular custom in a matter of such importance would almost certainly be noted and remembered. No, French felt that he might rely on Mr. Duke’s statement so far.