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.

"It 'ud be queer if I hadn't, by this time," he answered. "Oh yes, I've
thought things out pretty well, and I should say our people at the Yard
have come to the same conclusion that I have--I'm not conceited enough,
Mr. Allerdyke, to fancy that I'm the only person who's arrived at a
reasonable theory, not I?"

"Well--what is your theory?" asked Allerdyke.

"This," replied the detective. "The whole thing, the theft of the
Princess Nastirsevitch's jewels from your cousin, of Miss de Longarde's
or Lennard's jewels, was the work of a peculiarly clever gang--though it
may be of an individual--who made use of both Lydenberg and the French
maid as instruments, and subsequently murdered those two in order to
silence them forever. I say it may be the work of an individual--it's
quite possible that the man who killed the Frenchwoman is also the man