AN ENEMY OF SCOTLAND YARD

      INSPECTOR Ulton came to see Mr Linley today. I am glad to say that he has got used to me; the inspector, I mean. He just said, ‘You’re Mr Smethers, aren’t you?’ And I said I was. And he said, ‘Well, you’ll understand that all this is strictly private.’ And I said I would. And then he started talking to Mr Linley.

      I’d met Inspector Ulton before over the murder at Unge, and the shooting of Constable Slugger. Mr Linley had helped him a lot.

      ‘I’ve come to you again, Mr Linley,’ were his first words.

      ‘Is it Steeger again?’ asked Linley.

      ‘We don’t know who it is,’ said the inspector. ‘We usually know at the Yard who has done a murder. It’s not very difficult. Motive usually points straight at somebody; and we can easily find if he was in the neighbourhood at the time. Proving it is the only difficulty. This time we can’t even find out who it is. We thought you might help us, Mr Linley.’

      ‘What is it?’ said Linley.

      ‘It’s a bad case,’ said the inspector; ‘as bad a case as we’ve had for a long time.’

      ‘I’m sorry to hear that,’ I said.

      He didn’t pay any attention to me, but I somehow saw from his look that I’d said a silly thing. Bad cases were their job. If they stopped, where would Scotland Yard be? I was sorry as soon as I’d said it.

      ‘We got a letter at Scotland Yard last week,’ he said, ‘threatening that if Mr Cambell went again to his club, or Inspector Island went to watch a billiard-match at Piero’s, or Sergeant Holbuck played football either at the Scramblers Football Ground or the old Sallovians, each one of them that did so would be killed. Holbuck is one of our best football-players, and those are the only two grounds he ever plays on. Watching billiards at Piero’s was what Inspector Island always did when he could.’

      ‘But wait a moment, Inspector,’ said Linley. ‘That’s a preposterous threat. The man could never carry it out.’

      ‘Mr Cambell and Inspector Island are dead already,’ said Ulton.

      ‘Dead?’ said Linley. And I never saw him so flabbergasted.

      ‘Mr Cambell went to his club, the Meateaters, in Holne Street, the day that we got the letter, and was poisoned. And Inspector Island went to Piero’s next day to watch a game of billiards, and a piece of the wall above the door fell as he went in, and killed him.’

      ‘A piece of the wall fell?’ exclaimed Linley incredulously.

      ‘Yes,’ said the inspector. ‘It was in the papers, though very little about it, as they’ve not held the inquest yet. But we are working on the other case first, as we have a clue there.’

      ‘What is the clue?’ said Linley.

      ‘We’ve the finger-print of a waiter at the club, who disappeared on the night of the murder, before Mr Cambell was taken ill. Of course he must have given the poison, but we don’t know much about him or who he really is, and we don’t think he was the man who planned it all.’

      ‘Can I see the finger-print?’ asked Linley.

      And Inspector Ulton brought an envelope out of his pocket and took from it a sheet of paper, and on the paper was the finger-print, very completely in ink. It was one of two sheets of papers for members’ bills, and in the middle of it, very black, was the finger-print. Linley looked at it for a long time.

      ‘And Piero’s?’ he said at last.

      ‘That baffles us,’ said the inspector. ‘We have found out that the masonry that killed Island was dislodged by a small explosion that took place very effectively at a joint between two big stones. And the explosive was set off by a delicate mechanism that must have been inserted in the wall from the inside. We can find very little of the machine, not only because the explosion took place inside it, but because it was all mixed up with some stuff called thermite, which burns very fiercely, and which destroyed everything except a few small bars. Anyhow there was a machine that fired the explosive that brought down those pieces of masonry, but what we can’t find is any wires controlling it. The fire was soon put out, and the damage only local, and we have searched all round the door; both sides, above and below; but there’s no sign of a wire.’

      ‘Could one have been pulled away?’ asked Linley.

      ‘Not across the open without being seen by someone,’ said Ulton, ‘and there were plenty there. And not underground. We’ve searched; and we’ve made sure there’s no wire, or a channel that it could have run in. It must have been a time-fuse.’

      ‘Was Inspector Island as regular as all that?’ said Linley.

      ‘Well, he had regular habits,’ said Ulton, ‘and he got off duty at a certain hour and the game began at a certain time.’

      ‘To the very second?’ asked Linley.

      ‘Well, not to the very second,’ he said.

      ‘And it would have to be about half a second,’ went on Linley. ‘No, the time-fuse won’t do.’

      ‘I don’t suppose it will,’ said Ulton.

      And they were both silent awhile.

      ‘Well,’ said Linley after a bit, ‘I can tell you one thing. Whoever that waiter was …’

      ‘He called himself Slimmer,’ said Ulton.

      ‘Whoever he was,’ said Linley, ‘there’s something a bit deep about him. Deeper than you’ve had time to go yet, I mean. That finger-print shows you that. When did he make it?’

      ‘It was found after he’d gone,’ said Ulton. ‘What’s odd about it? We find thousands of finger-prints.’

      ‘Simply,’ said Linley, ‘that a man who is committing a murder doesn’t make a finger-print in ink right in the middle of a sheet of paper, quite so neat and tidy as that, and then leave it where the police can find it handily.’

      ‘What then?’ said Ulton.

      ‘Why, it’s not his finger-print. It’s some kind of fake. So that you are dealing with very queer people; people clever enough to forge finger-prints, which I have never heard of being done. Have you?’

      But Inspector Ulton would not say what they knew at the Yard and what they didn’t know.

      ‘I might have,’ he said.

      ‘It might be done on rubber by a good forger, I should think,’ went on Linley. ‘But the people that did that might be capable of carrying out their threats, which at first I hardly thought possible. Now about the explosion at Piero’s. That must have been controlled by someone who could actually see Island coming. He might have had warning that he was coming when he was fifty yards away, or any other distance, but that would never have been exact enough to kill him. He must have seen him go into Piero’s.’

      ‘And, if he did, how could he make the thing explode?’ said Ulton.

      ‘That’s what we’ve got to think about,’ said Linley. ‘What houses are there from which he could see the inspector going up to the door?’

      ‘There’s several,’ said the inspector.

      ‘And