As he sat a little later gazing out on to the smiling Fifeshire country, he went over once more, point by point, that portion of Cosgrove’s alibi which he had already checked. So far as he had gone it certainly seemed to him very complete. In the first place, not only was the journey north made with, so far as he could ascertain, a quite genuine purpose, but the selection of that particular night was reasonably accounted for. The arrangement for it had been made at least as early as the previous Monday, which, again, would be a reasonable time in advance. Tanner could see nothing in any way suspicious or suggestive of a plant about the whole business. Then, coming to details, the missing of the train at King’s Cross might of course have been faked, but there was no evidence to support such a supposition. On the contrary, everything he had learnt seemed to prove it genuine. But even if it had been a plant, it was demonstrated beyond a shadow of doubt that Cosgrove _had_ missed the 7.15 p.m. as he said, and that, further, he _had_ travelled to Montrose by the 10.30. Even as the case stood Tanner felt bound to accept the alibi, but if he could confirm Cosgrove’s statement of his visit to his rooms at 7.45 or 8 o’clock, and to the Follies about 10.00, any last shred of doubt that might remain must be dispelled. This, he decided, would be his next task. The following morning, therefore, he returned to Knightsbridge. Here, keeping his eye on Cosgrove’s door, he strolled about for nearly an hour before he was rewarded by seeing it open and Cosgrove emerge and disappear towards Piccadilly. He allowed some ten minutes more to elapse, then he walked to the door and rang. It was opened by the same dark, clean-shaven butler who had admitted him before. The man recognised his visitor, evidently with suspicion. ‘Mr Reginald Willoughby, the Albany?’ he asked with sarcasm, and a thinly veiled insolence in his tone. ‘That’s all right,’ Tanner answered easily. ‘I know my name is not Willoughby. It’s Tanner’—he handed over his real card—‘and if you’ll invite me in for a moment or two I’ll show you my credentials so that you’ll have no more doubt.’ The butler was evidently impressed, and proffering the suggested invitation, led the way to a small sitting room. ‘Mr Ponson he phoned the Albany,’ he explained, ‘and they said there weren’t no one of that name there, so we was wondering about your little game.’ Tanner, following his usual custom, rapidly sized up his man, and decided how he should deal with him. With the veneer of his calling removed the Inspector imagined he might prove a braggart, a bully, and a coward. He therefore took a strong line. ‘I suppose you know,’ he began, without heeding the other’s remark, ‘that Mr Cosgrove Ponson is under serious suspicion of the murder of his uncle, Sir William, at Luce Manor?’ It was evident this was the last thing the butler had expected to hear. He stared at the Inspector in amazement.