“There’s plenty of the ancient about it still, for all that,” observed Chettle, with a dry laugh.  “There was more than enough of it for Lydenberg the other day, at any rate.  Now, then, you remember what it said on the postcard—­he was to walk down the High Street, on the left-hand side, at eleven o’clock?  Very well—­down the High Street he walks, on this side which we are now—­he strolls along, by these old houses, looking about him, of course, for the person he was to meet.  The few people who were about down here that morning, and who saw him, said that he was looking about from side to side.  And all of a sudden a shot rang out, and Lydenberg fell—­just here—­right on this very pavement.”

He pulled Allerdyke up in a narrow part of the old street, jointed to the flags, and then to the house behind them—­an ancient, ramshackle place, the doors and windows of which were boarded up, the entire fabric of which showed unmistakable readiness for the pick and shovel of the house-breaker.  And he laid a hand on one of the shattered windows, close by a big hole in the decaying wood.

“There’s no doubt the murderer was hidden behind this shutter, and that he fired at Lydenberg from it, through this hole,” he said.  “So, you see, he’d only be a few feet from his man.  He was evidently a good shot, and a fellow of resolute nerve, for he made no mistake.  He only fired once, but he shot Lydenberg clean through the heart, dead!”

“Anybody see it happen?” asked Allerdyke, staring about him at the scene of the tragedy, and thinking how very ordinary and commonplace everything looked.  “I suppose there’d be people about, though the street, at this end, anyway, isn’t as busy as it once was?”

“Several people saw him fall,” answered Chettle.

“They say he jumped, spun round, and fell across the pavement.  And they all thought it was a case of suicide.  That, of course, gave the murderer a bigger and better chance of making off.  You see, as these people saw no assailant, it never struck ’em that the shot had been fired from behind this window.  When they collected their thoughts, found it wasn’t suicide, and realized that it was murder, the murderer was—­Lord knows where!  From behind these old houses, Mr. Allerdyke, there’s a perfect rabbit-warren of alleys, courts, slums, twists, and turns!  The man could slip out at the back, go left or right, mix himself up with the crowd on the quays and wharves, walk into the streets, go anywhere—­all in a minute or two.”

“Clever—­very clever!  You’ve no clue?” asked Allerdyke.

“None; not a scrap!” replied the detective.  “Bless you, there’s score of foreigners knocking about Hull.  Scores!  Hundreds!  We’ve done all we can, the local police and myself—­we’ve no clue whatever.  But, of course, it was done by one of the gang.”

“By one of the gang!” exclaimed Allerdyke.  “Ah you’ve got a theory of your own, then?”

Chettle laughed quietly as they turned and retraced their steps up the street.