in the entrance hall of the langham freyberger drew a long, black, poisonous-looking cheroot from his pocket and lit it.

then he buttoned his overcoat and prepared to depart. he felt jubilant. the whole of the pieces of the puzzle had fallen into their places under the influence of his intellect, and now this new sidelight had pointed at the possible road to the absolute and final move, which would allow him to place his hand upon the creator of the puzzle, and say: “you are mine.”

he was just going down the steps when a voice from behind said, “excuse me.”

he turned and saw hellier.

“i would like a moment’s conversation with you,” said the barrister.

“certainly, certainly,” said the other, in a not too amiable voice. “what can i do for you?”

“if you will allow me to walk a few hundred yards with you, i will explain myself. please don’t think i want to interfere in this case, but i have sworn to give all the help in my power, and i think i may be able to make a suggestion to you that may be useful.”

“humph.”

“i have made a special study of forensic medicine and criminology, and this has occurred to me.

“i will tell you what i think in a few words. this müller accomplished a deeply reasoned out and intricate crime in paris eight years ago. well, having done that, his reason withdrew herself, exhausted possibly, but the lust for killing excited by the crime, remained and grew and had to be satisfied. he strangled three people.

“we know of lots of cases where a lunatic has a grudge against the whole female or male sex, and kills for the pleasure of killing. it is rarer for a man of this description to have a grudge against the whole of humanity and to murder indiscriminately, but it occurs.

“we find these people perfectly sane in other ways; they are just tigers let loose when their reason becomes weakened.

“so we have müller, a man of profound intellect, suddenly, under the thirst of blood, turned into a killing machine. he kills three people, no more, for the fit passes. he is gorged for years, till he commits a new murder and the fit returns.”

“proceed,” said freyberger, in a hard voice; for what hellier had just said was the very thing he had been thinking to himself.

“well, as müller did eight years ago, so, in all probability, he will do again. he has murdered a man in cumberland. the thirst for blood, or rather human life, will most probably seize him again. and all you have to do to catch him is to wait. i will wager my reputation that this beast will repeat his actions like some horrible automaton, and that within the next few days you will have a case of motiveless murder to investigate, and that if you catch the criminal it will be müller.”

freyberger did not reply. what hellier had just said was exactly what he (freyberger) had been thinking.

it is not pleasant to find one’s astuteness matched. he had put all his energy and mind into the gyde case, and here was a stranger pointing out to him the course to take for the completion of the affair; and, worst of all, the right course.

he quite forgot that it was due to hellier’s researches that these subsidiary crimes had been connected with the lefarge case.

he was, in fact, human, and he was jealous.

“what you have said,” he replied, “may have something in it.”

“i think, myself, it may have a good deal in it,” replied hellier, nettled somewhat at the other’s assumed indifference and the chilliness of his tone.

“well,” said freyberger, “the matter is in our hands, and you may be sure everything will be done that is needful. we do not, as a rule, require outside help or suggestions in our work. i wish you good night.”

“that’s the professional detective all over,” thought hellier, as he watched the departing figure of freyberger. “they work in one set groove, they have ideas handed down from generation to generation. i was amazed at this man’s perspicuity at first, and now i find him just one of a class. well, if he doesn’t see much in my idea i do, and i will keep my eyes open, and if i see a chance i will profit by it.”