Kennedy's first move was to go downtown to the old building opposite the City Hall and visit the post-office inspectors.

"I've heard of the government's campaign against the medical quacks who are using the mails," he introduced when we at last found the proper inspector. "I wonder whether you know a Dr. Adam Loeb?"

"Loeb?" repeated the inspector, O'Hanlon, who was in charge of the investigation which was then in progress. "Of course we know Loeb—a very slippery customer, too, with just enough science at his command to make the case against him difficult.

"I suppose," went on O'Hanlon, "you know that in Europe the popular furore about radium and its applications appeared earlier than it did here. But now we have great numbers of dishonest and fake radium cure establishments. Usually they have neither radium nor knowledge. They promise a cure, but they can't even palliate the trouble. Loeb has some radium, I guess, but that's about all."

"I think I'd like to visit the 'doctor' and his 'medical museum,'" ventured Kennedy when O'Hanlon had finished describing the case to us.

"Very well," agreed O'Hanlon. "Our cases against the quacks are just about completed. I've heard a great deal about you, Mr. Kennedy. I think I may trust you."

The inspector paused. "Tomorrow," he added, looking at us significantly, "we have planned a simultaneous raid of all of them in the city. However, there's no objection to your seeing Dr. Loeb, if you'll be careful to give no hint that something is about to be pulled off. I'm sure any new evidence we may get against him will be quite welcome."

"I'd like to see him in action before the raid," hastened Craig.

"Well, I think the best way, then, for you to get at him," advised the inspector, "would be to adopt the method my investigators use with these fakers. I mean for one or the other of you to pose as a prospective patient. Only don't let him treat you too much with any of those electrical things of his."

Craig glanced over at me whimsically.

"Oh," I said good-humoredly, "I'll be the goat, if that's what you're going to ask me."

Craig laughed.

"Come in tomorrow," called the inspector as we left. "I'd like to hear what happens and I may be able to add something to what you find out."

We found Dr. Loeb established in a palatial suite of offices in an ultra-modern office building. Outside was what he called his "medical museum." It was a grewsome collection of wax figures and colored charts well calculated to prepare one for the worst. At the end of the room was a huge sign bearing his name and the words, "Positive Cure for Cancer Without Cautery or the Knife."

There were no cappers or steerers about the place, though I have no doubt he had them working for him outside to bring in business. Instead, we were met by a very pretty, fluffy-haired girl, evidently the doctor's secretary. She, I gathered, was the Miss Golder whom Lionel had mentioned. In fact, I felt that she was really much above the level of such a position.

Loeb's office was elaborately equipped. There were static machines, electric coils, high frequency appliances, X-ray outfits, galvanic and faradic cabinets, electric light reflectors of high power, light bath cabinets, electric vibrators, high pressure nebulizers and ozonizers—everything, as Craig expressed it later, to impress the patient that Loeb could cure any disease the flesh was heir to. I know that it impressed me.

The doctor himself was a pompous man of middle age, with a very formidable beard and a deep voice that forbade contradiction.

"I've come to you on the recommendation of a patient of yours," began Craig, adding hastily, "not for myself, but for my friend here, whom I'm afraid isn't very well."

The doctor eyed me through his gold-rimmed spectacles. Already I began to feel shaky.

"Who recommended you?" he asked casually.

"My friend, Mr. Darius Moreton of Norwood. I suppose you remember him?"

"Oh, very well, very well. A most peculiar case, that of the Moretons. I have succeeded in prolonging their lives beyond what anyone else could have done. But I fear that they haven't all followed my treatment. You know, you must put yourself entirely in my hands, and there is a young doctor out there, I believe, whom they have also. That isn't fair to me. I wonder whether you are acquainted with my methods of treatment?"

Kennedy shook his head negatively.

"Miss Golder," the doctor called, as the fluffy-haired secretary responded quickly, "will you give these gentlemen some of my booklets on the Loeb Method."

Miss Golder took from a cabinet several handsomely printed pamphlets extolling the skill and success of Dr. Loeb. Like everything else about him, no expense had been spared to impress the reader.

As Miss Golder left the office, Dr. Loeb began a rapid examination of me, using an X-ray machine. I am sure that if I had not received a surreptitious encouraging nod from Craig now and then, I should have been ready to croak or cash in, according to whichever Dr. Loeb suggested—probably the latter, for I could not help thinking that a great deal of time was spent in mentally X-raying my pocketbook.

When he finished, the doctor shook his head gravely. Of course I was threatened. But the thing was only incipient. Still, if it were not attended to immediately it was only a question of a short time when I might be as badly, as the wax figures and charts outside. I had fortunately come just in time to be saved.

"I think that with the electrical treatment we can get rid of that malignant growth in a month," he promised, fixing a price for the treatment which I thought was pretty high, considering the brief time he had actually spent on me, and the slight cost of electric light and power.

I paid him ten dollars on deposit, and after a final consultation we left the doctor's office. I was to return for a treatment in a couple of days.

We turned out of the entrance of the office building just as scores of employÉs were hurrying home. As we reached the door, I felt Kennedy grasp my arm. I swung around. There, in an angle of the corridor, I caught sight of a familiar figure. Dr. Goode was standing, evidently waiting for someone to come out. There were several elevators and the crowd of discharging passengers was thick. He had been so intent on looking for someone he expected, apparently, that he had missed us.

Kennedy drew me on into the doorway of the building next door, from which we could observe everyone who went in and out of the skyscraper in which Dr. Loeb had his offices.

"I wonder what he's down here for," scowled Kennedy.

"Perhaps he's doing some detective work of his own," I suggested.

"Lionel Moreton said that Miss Golder and he used to be intimate," ruminated Kennedy. "I wonder if he's waiting for her?"

We did not have long to wait. It was only a few minutes when Kennedy's surmise proved correct. Miss Golder and Dr. Goode came out, and turned in the direction of the railroad station for Norwood. He was eagerly questioning her about something, perhaps, I imagined, our visit to Dr. Loeb. What did it mean?

There was no use and it was too risky to follow them. Kennedy turned and we made our way uptown to the laboratory, where he plunged at once into an examination of the blood specimens he had taken from the Moretons and of the peculiar porcelain cone which he had picked up in the rubbish pile between the two houses.

Having emptied the specimens of blood in several little shallow glass receptacles which he covered with black paper and some very sensitive films, he turned his attention to the cone. I noted that he was very particular in his examination of it, apparently being very careful to separate whatever it was he was looking for on the inside and the outside surfaces.

"That," he explained to me at length as he worked, "is what is known as a Berkefeld filter, a little porous cup, made of porcelain. The minute meshes of this filter catch and hold bacteria as if in the meshes of a microscopic sieve, just like an ordinary water filter. It is so fine that it holds back even the tiny bacillus fluorescens liquefaciens which are used to test it. These bacilli measure only from a half to one and one-and-a-half micromillimeters in diameter. In other words 130,000 germs of half a micromillimeter would be necessary to make an inch."

"What has it been used for?" I ventured.

"I can't say, yet," he returned, and I did not pursue the inquiry, knowing Kennedy's aversion to being questioned when he was not yet sure of his facts.

It was the next day when the post-office inspectors, the police and others who had been co-operating had settled on the raid not only of Dr. Loeb's but of all the medical quacks who were fleecing the credulous of the city out of hundreds of thousands of dollars a year by one of the most cruel swindles that have ever been devised.

For the time, Kennedy dropped his investigations in the laboratory and we went down to O'Hanlon's office, where a thick batch of warrants, just signed, had been received.

Quickly O'Hanlon disposed his forces so that in all parts of the town they might swoop down at once and gather in the medical harpies. Dr. Loeb's stood first on the list of those which O'Hanlon decided to handle himself.

"By the way," mentioned O'Hanlon as we hurried uptown to be ready in time, "I had a letter from Darius Moreton this morning threatening me with all kinds of trouble unless we let up on Dr. Loeb. It's pretty hard to keep a big investigation like this secret, but I think we've planned a little surprise for this morning."

With the post-office inspector we climbed into a patrol wagon with a detail of police who were to make a general round-up of the places on Forty-second Street.

As the wagon backed up to the curb in front of the building in which Loeb's office was, the policemen hopped out and hurried into the building before a crowd could collect. Unceremoniously they rushed through the outer office, headed by O'Hanlon.

Quickly though the raid was executed, it could not be done without some warning commotion. As we entered the front door of the office, we could just catch a glimpse of a man retreating through a back door. There was something familiar about his back, and Kennedy and I started after him. But we were too late. He had fled without even waiting for his hat, which lay on Miss Golder's desk, and had disappeared down a back stairway which had been left unguarded.

"Confound it," muttered O'Hanlon, as we returned, "Loeb hasn't been here today. Who was that?"

"I don't know," replied Craig, picking up the hat, underneath which lay a package.

He opened the package. Inside were half a dozen Berkefeld filters, those peculiar porcelain cones such as we had found out at Norwood.

Quickly Craig ran his eye over the mass of papers on Miss Golder's desk. He picked up an appointment book and turned the pages rapidly. There were several entries that seemed to interest him. I bent over. Among other names entered during the past few days I made out both "Moreton" and "Dr. Goode." I recalled the letter which O'Hanlon had received from Moreton. Had he or someone else got wind of the raids and tipped off Dr. Loeb?

Above the hubbub of the raid I could hear O'Hanlon putting poor little Miss Golder through a third degree.

"Who was it that went out?" he shouted into her face. "You might as well tell. If you don't it'll go hard with you."

But, like all women who have been taken into these get-rich-quick swindles, she was loyal to a fault. "I don't know," she sobbed, dabbing at her eyes with a bit of a lace handkerchief.

Nor could all of O'Hanlon's bulldozing get another admission out of her except that it was a "stranger." She protested and wept. But she even rode off in the patrol wagon with the rest of the employÉs unmoved.

Whom was she shielding? All we had was the secretary, a couple of cappers, and half a dozen patients, regular and prospective, who had been waiting in the office. We had a wagon-load of evidence, including letters and circulars, apparatus of all kinds, medicines, and pills. But there was nothing more. Craig did not seem especially interested in the mass of stuff which the police had seized.

In fact the only thing that seemed to interest him was the man who had disappeared. We had his hat and the package of filters. Craig picked up the hat and examined it.

"It's a soft hat and consequently doesn't tell us very much about the shape of his head," he remarked. Then his face brightened. "But he couldn't have left anything much better," he remarked complacently, as he went over to one of the little wall cabinets which the towel service companies place over wash-basins in offices. He took from it a comb and brush and wrapped them up carefully.

I looked at the hat also. There was no name in it, not even the usual initials. What did Craig mean?

Other raids in various parts of the city proved far more successful than the one in which we had participated and O'Hanlon quickly forgot his chagrin in the reports that soon came piling in. As for ourselves we had no further interest except in the disposition of this case, and Craig decided shortly to go back to work again in the laboratory among his test-tubes, slides, and microscopes.

"I will leave you to follow the cases against the quacks, particularly Dr. Loeb and Miss Golder, Walter," he said. "By the way, you saw me take that hair brush. I wish I had a collection of them. In some way you must get me a hair brush from Dr. Goode. You'll have to take a trip out to Norwood. And while you are there, get the brushes from Darius Moreton and Lionel. I don't know how you'll get Goode's, but Myra will help you with the others, I'm sure."

He turned to his work and was soon absorbed in some microscopic studies, leaving me no chance to question him about his strange commission.