castle, but it was used only by suburbantrains or for the royal private car.

  Muller did not intend to burden his brain with unnecessary facts, sowith his usual thoroughness he left the further investigation of whatlay beyond the gate, until he had searched the garden thoroughly. Buteven for his sharp eyes there was no trace to be found that would tellof the night visit of the murderer.

  "In which of the pails did you put the key to the side door?" he asked.

  "In the first pail on the right hand side. But be careful, sir; there'sa nail sticking out of the post there. The wind tore off a piece of woodyesterday."

  The warning came too late. Muller's sleeve tore apart with a sharp soundjust as Johann spoke, for the detective had already plunged his handinto the pail. The bottom of the bucket was easy to reach, as this onehung much lower than the others. Looking regretfully at the rent inhis coat, Muller asked for needle and thread that he might repair itsufficiently to get home.

  "Oh, don't bother about sewing it; I'll lend you one of mine," exclaimedJohann. "I'll carry this one home for you, for I'm not going to stayhere alone--I'd be afraid. I'm going to a friend's house. You canfind me there any time you need me. You'd better take the key of theapartment and give it to the police."

  The detective had no particular fondness for the task of sewing, andhe was glad to accept the valet's friendly offering. He was ratherastonished at the evident costliness of the garment the young man handedhim, and when he spoke of it, the valet could not say enough in praiseof the kindness of his late master. He pulled out several other articlesof clothing, which, like the overcoat, had been given to him by Fellner.Then he packed up a few necessities and announced himself as ready tostart. He insisted on carrying the torn coat, and Muller permitted itafter some protest. They carefully closed the apartment and the house,and walked toward the centre of the city to the police station, whereMuller lived.

  As they crossed the square, it suddenly occurred to Johann that he hadno tobacco. He was a great smoker, and as he had many days of enforcedidleness ahead of him, he ran into a tobacco shop to purchase asufficiency of this necessity of life.

  Muller waited outside, and his attention was attracted by a large greyUlmer hound which was evidently waiting for some one within the shop.The dog came up to him in a most friendly manner, allowed him to pat itshead, rubbed up against him with every sign of pleasure, and would notleave him even when he turned to go after Johann came out of the shop.Still accompanied by the dog, the two men walked on quite a distance,when a sharp whistle was heard behind them, and the dog became uneasy.He would not leave them, however, until a powerful voice called"Tristan!" several times. Muller turned and saw that Tristan's masterwas a tall, stately man wearing a handsome fur overcoat.

  It was impossible to recognise his face at this distance, for thesnowflakes were whirling thickly in the air. But Muller was notparticularly anxious to recognise the stranger, as he had his head fullof more important thoughts.

  When Johann had given his new address and remarked that he would callfor his coat soon, the men parted, and Muller returned to the policestation.

  The next day the principal newspaper of the town printed the followingnotice:

  THE GOLDEN BULLET

  It is but a few days since we announced to our readers the sad news of the death of a beautiful woman, whose leap from her window, while suffering from the agonies of fever, destroyed the happiness of an unusually harmonious marriage. And now we are compelled to print the news of another equally sad as well as mysterious occurrence. This time, Fate has demanded the sacrifice of the life of a capable and promising young man. Professor Paul Fellner, a member of the faculty of our college, was found dead at his desk yesterday morning. It was thought at first that it was a case of suicide, for doors and windows were carefully closed from within and those who discovered the corpse were obliged to break open one of the doors to get to it. And a revolver was found lying close at hand, upon the desk. But this revolver was loaded in every chamber and there was no other weapon to be seen in the room. There was a bullet wound in the left breast of the corpse, and the bullet had penetrated the heart. Death must have been instantaneous.

  The most mysterious thing about this strange affair was discovered during the autopsy. It is incredible, but it is absolutely true, as it is vouched for under oath by the authorities who were present, that the bullet which was found in the heart of the dead man was made of solid gold. And yet, strange as is this circumstance, it is still more a riddle how the murderer could have escaped from the room where he had shot down his victim, for the keys in both doors were in the locks from the inside. We have evidently to do here with a criminal of very unusual cleverness and it is therefore not surprising that there has been no clue discovered thus far. The only thing that is known is that this murder was an act of revenge.

  The entire city was in excitement over the mystery, even the policestation was shaken out of its usual business-like indifference. Therewas no other topic of conversation in any of the rooms but themystery of the golden bullet and the doors closed from the inside. Theattendants and the policeman gathered whispering in the corners,and strangers who came in on their own business forgot it in theirexcitement over this new and fascinating mystery.

  That afternoon Muller passed through Horn's office with a bundle ofpapers, on his way to the inner office occupied by his patron, Chief ofPolice Bauer. Horn, who had avoided Muller since yesterday although hewas conscious of a freshened interest in the man, raised his head andwatched the little detective as he walked across the room with hisusual quiet tread. The commissioner saw nothing but the usual humblebusiness-like manner to which he was accustomed--then suddenlysomething happened that came to him like a distinct shock. Mullerstopped in his walk so suddenly that one foot was poised in the air. Hisbowed head was thrown back, his face flushed to his forehead, and thepapers trembled in his hands. He ran the fingers of his unoccupied handthrough his hair and murmured audibly, "That dog! that dog!" It wasevident that some thought had struck him with such insistence as torender him oblivious of his surroundings. Then he finally realised wherehe was, and walked on quickly to Bauer's room, his face still flushed,his hands trembling. When he came out from the office again, he was hisusual quiet, humble self.

  But the commissioner, with his now greater knowledge of the little man'sgifts and past, could not forget the incident. During the afternoonhe found himself repeating mechanically, "That dog--that dog." But thewords meant nothing to him, hard as he might try to find the connection.

  When the commissioner left for his home late that afternoon, Mullerre-entered the office to lay some papers on the desk. His duties over,he was about to turn out the gas, when his eye fell on the blotter onHorn's desk. He looked at it more closely, then burst into a loudlaugh. The same two words were scribbled again and again over the whitesurface, but it was not the name of any fair maiden, or even the titleof a love poem; it was only the words, "That dog--"

  Several days had passed since the discovery of the murder. Fellner hadbeen buried and his possessions taken into custody by the authoritiesuntil his heirs should appear. The dead man's papers and affairs werein excellent condition and the arranging of the inheritance had beenquickly done. Until the heirs should take possession, the apartment wassealed by the police. There was nothing else to do in the matter, andthe commission appointed to make researches had discovered nothing ofvalue. The murderer might easily feel that he was absolutely safe bythis time.

  The day after the publication of the article we have quoted, Mullerappeared in Bauer's office and asked for a few days' leave.

  "In the Fellner case?" asked the Chief with his usual calm, and Mullerreplied in the affirmative.

  Two days later he returned, bringing with him nothing but a singlelittle notice.

  "Marie Dorn, now Mrs. Kniepp," was one line in his notebook, and besideit some dates. The latter showed that Marie Dorn had for two years pastbe
en the wife of the Archducal Forest-Councillor, Leo Kniepp.

  And for one year now Professor Paul Fellner had been in the town, afterhaving applied for his transference from the university in the capitalto this place, which was scarce half an hour's walk distant from thehome of the beautiful young woman who had been the love of his youth.

  And Fellner had made his home in the quietest quarter of the city, inthat quarter which was nearest the Archducal hunting castle. He hadlived very quietly, had not cultivated the acquaintance of the ladies ofthe town, but was a great walker and bicycle rider; and every Saturdayevening since he had been alone in the house, he had sent his servantto the theatre. And it was on Saturday evenings that Forest-CouncillorKniepp went to his Bowling Club at the other end of the city, and didnot return until the last train at midnight.

  And during these evening