“I look at it like this, sir. The first murder was a prepared murder. The murderer was able to choose his opportunity and his place as carefully as he liked: and he had plenty of time to work out the angles. There are people with minds like that. The sort of mind that can cope with a double-dummy bridge problem and work out all the variations—you know, if South ducks the third round of trumps then West must put up his queen and throw away a small heart at round six instead of a small diamond.”
“Hrrmp!” said the Commissioner.
“But you face the same man with a snap decision in the actual play of the hand: something that’s going to mean the difference between making his contract and going down: with everybody watching him and waiting for him to play: that’s when expensive mistakes get made.”
“Well,” said the Commissioner, who was not a bridge player, “I hope you’re right. Because, make no mistake about it, we want this murderer.”
VI
The checking of alibis is neither an easy nor a certain business. There are too many unknowns to make it a mathematical process. And even the known facts have a way of varying themselves in the process of verification.
Sergeant Plumptree visited a large catering establishment at the Wellington Street end of the Strand. He had in his pocket a statement by Bob Horniman who, it appeared, had had his evening meal there the night before. “I got there at about half-past six,” the statement said, “I went into the first dining-room you come to. I can’t remember which table I sat at. It was somewhere on the right. I left at about half-past seven.”
Sergeant Plumptree had some difficulty, to start with, in making up his mind which of the many rooms answered the description of “the first dining-room you come to”. There were three at almost the same distance from the main entrance. He got on the telephone and spoke to Hazlerigg who had another word with Bob Horniman.
“It’s the one straight ahead,” he reported.
“There are two straight ahead,” said Sergeant Plumptree.
“Then check them both,” said Hazlerigg.
Sergeant Plumptree then interviewed, in turn, a junior floorwalker, who clearly knew nothing, a senior floorwalker, who had something of the look of a rural dean, and finally an attractive woman of about thirty who seemed, despite her youth, to be a senior executive. She proved surprisingly helpful, and organised Sergeant Plumptree’s search for him. “It can’t have been the Minervan Room,” she said, “because that closes when the teas are finished. So it must have been the Arcadian Salon. On the right, you said. Well, there are three or four waitresses who might have served a table on the right. The shift is from midday to eight, so they should be available now.” She rang a number of bells, pressed two coloured buttons on her desk and spoke into a house telephone—presently Sergeant Plumptree was showing a photograph to one thin blonde, one stout blonde, one brunette and one nondescript waitress. None of them recognised it.
“Perhaps if you could tell me which table…?”
“Well, that’s exactly what I can’t do,” said Sergeant Plumptree. It had occurred to him previously that it might have been simpler to have brought Bob Horniman along with him, but apparently police etiquette forbade it.
As he was going the manageress said:
“I see that this gentleman states that he was at his table for about an hour. I’m sure that the girls would have remembered that. Six-thirty or seven-thirty is a very good time for tips and if anyone sits on for too long after their meal they’ll get up to almost any dodge to get rid of them. Why, I’ve even known them spill a whole pot of hot coffee.”
The girls were summoned again and the point was put to them. They were all quite certain that the young man in the picture had not sat at any table for which they were responsible for anything like an hour. “He might have been in and out for a quick snack,” said the thin blonde, summing it up, “but not an hour.” The others concurred.
Sergeant Plumptree came away thoughtfully.
VII
“I caught the six-forty from Charing Cross,” Miss Cornel had said. “I had to hurry to do that. Not that I need have worried. It didn’t start till about twenty past seven. It was absolutely full, so I had to stand. It’s an electric, non-corridor train. You