On leaving Cosgrove Ponson, Inspector Tanner walked slowly up the shady side of Regent Street, his mind still running on the statement to which he had just listened. To test its truth was his obvious first duty, and as he sauntered along he considered the quickest and most thorough means of doing so. From the very nature of the story he felt inclined to believe it. Too much independent testimony seemed to be available for the alibi to be a fraud.
And if this was so, he, Tanner, was on the wrong track, and was wasting time. He had already lost nearly a week over Austin, and all the time he was working on these blind alleys the real scent was getting cold. But as he reviewed the facts he had learnt, he felt he could hardly have acted otherwise than as he had.
He considered Cosgrove’s statement point by point. Firstly, was it true he could only have gone to Scotland on the night in question of all others? In answer to this it should be easy to find out if he really was at the Duchess of Frothingham’s on the same afternoon. Then the missing of the train at King’s Cross must be known to several persons—the clerk at the stationmaster’s office, the barmaid who sold the cigars, as well possibly as the sleeping-car attendant, and the telegraph-office clerk, and copies of the wires to Grantham and to Montrose should be available. He was not sure that confirmation of Cosgrove’s visit to the Empire would be obtainable, though some attendant might have noticed him. But there should be ample proof of his call on Miss Belcher at the Follies Theatre. Not only would there be the testimony of Miss Belcher herself, but some of the many attendants must almost certainly have seen him. Then, if Cosgrove was not actually seen leaving London by the 10.30 p.m., he must have been observed in that train at Grantham, where his luggage was handed in to him. Finally, to ensure that he did not leave the train there and return to Luce Manor, as well as to test the genuineness of the whole journey, Tanner could see Colonel Archdale, the horse owner of Montrose.
And then another point struck him. What, he wondered, were the precise relations between Cosgrove Ponson and Miss Betty Belcher? From their demeanour at the restaurant, they were certainly on pretty intimate terms. In this case could Miss Belcher’s testimony to Cosgrove’s call at the theatre be relied on? Here was what undoubtedly might be a flaw in the alibi, and he felt he must handle this part of it with special care.
As he reached this point in his cogitations he arrived at the goal of his walk—a small but extremely fashionable tobacconist’s in Oxford Street. Handing in his card, he asked to see the manager.
He was shown into a small, neatly-furnished office, and there after a few minutes a tall young man in a grey frock coat joined him.
‘Hallo, Tony,’ said the Inspector when the door had closed.
The newcomer greeted his visitor breezily.
‘Why, Tanner, old son,’ he cried, ‘how goes it? You’re a stranger, you are. And what’s blown you in today?’
‘Business as usual. I want your help.’