“Never mind the expense,” said Meeks; “we’ll try it.”

The sleuth led him back to the Waldorf.  “Engage a couple of bedrooms and a parlour,” he advised, “and let’s go up.”

This was done, and the two were shown to a superb suite on the fourth floor.  Meeks looked puzzled.  The detective sank into a velvet armchair, and pulled out his cigar case.

“I forgot to suggest, old man,” he said, “that you should have taken the rooms by the month.  They wouldn’t have stuck you so much for ’em.

“By the month!” exclaimed Meeks.  “What do you mean?”

“Oh, it’ll take time to work the game this way.  I told you it would cost you more.  We’ll have to wait till spring.  There’ll be a new city directory out then.  Very likely your sister’s name and address will be in it.”

Meeks rid himself of the city detective at once.  On the next day some one advised him to consult Shamrock Jolnes, New York’s famous private detective, who demanded fabulous fees, but performed miracles in the way of solving mysteries and crimes.

After waiting for two hours in the anteroom of the great detective’s apartment, Meeks was shown into his presence.  Jolnes sat in a purple dressing-gown at an inlaid ivory chess table, with a magazine before him, trying to solve the mystery of “They.”  The famous sleuth’s thin, intellectual face, piercing eyes, and rate per word are too well known to need description.

Meeks set forth his errand.  “My fee, if successful, will be $500,” said Shamrock Jolnes.

Meeks bowed his agreement to the price.

“I will undertake your case, Mr. Meeks,” said Jolnes, finally.  “The disappearance of people in this city has always been an interesting problem to me.  I remember a case that I brought to a successful outcome a year ago.  A family bearing the name of Clark disappeared suddenly from a small flat in which they were living.  I watched the flat building for two months for a clue.  One day it struck me that a certain milkman and a grocer’s boy always walked backward when they carried their wares upstairs.  Following out by induction the idea that this observation gave me, I at once located the missing family.  They had moved into the flat across the hall and changed their name to Kralc.”

Shamrock Jolnes and his client went to the tenement house where Mary Snyder had lived, and the detective demanded to be shown the room in which she had lived.  It had been occupied by no tenant since her disappearance.

The room was small, dingy, and poorly furnished.  Meeks seated himself dejectedly on a broken chair, while the great detective searched the walls and floor and the few sticks of old, rickety furniture for a clue.

At the end of half an hour Jolnes had collected a few seemingly unintelligible articles—­a cheap black hat pin, a piece torn off a theatre programme, and the end of a small torn card on which was the word “left” and the characters “C 12.”