Forrester nodded.
"Then you would carry those lines below the surface. In other words, the lines you had laid out on the surface would be a guide to you when you got below it."
Again Forrester nodded.
"All right," said Humphrey. "I think you've got my idea about this case, and what I mean by solving it by triangulation. You will take the people, and the events which have occurred, and use them as your prominent landmarks; that is, points for your triangles. You will then study what lies between those landmarks, and also what lies under the surface. By that means I think you will eventually discover some clues that will be worth while.
"For example; take Mr. Nevins, who was the last victim of the 'Friends of the Poor,' as the first point of your triangle. Take his bank as the second, and his home as the third point. Instead of measuring the distance between these points by feet or rods, measure it by people and events. Set down, just as you would the figures of a survey, the names of his friends and acquaintances, the men with whom he has done business, and any little out-of-the-way events which have taken place in his life, so far as you can ascertain them. Do this with the other people who have been concerned in the blackmailing activities of this band. By arranging your triangles so they will overlap if possible, you will get at a starting point. Somewhere the lines will cross, and at the point of intersection a definite clue may form."
"Mr. Humphrey," laughed Forrester, "you are giving me a man's-size job."
"I know it!" admitted Humphrey. "But the man who solves this case has got to put more than ordinary brains and ability into it. You have got to forget the old rules and theories and formulas. That is why the experienced detectives are falling down. They can't forget the rules! When you suggested a while ago that you thought of turning detective, I immediately saw its possibilities. Your engineering training has taught you how to study cause and effect, and work out plans for meeting unusual conditions. You start with a mind trained to solve difficult problems, but at the same time your mind is free of all the traditions of the detective craft. Things they wouldn't notice, or consider important if they did, will impress themselves upon you and start a train of thought.
"Now then," exclaimed Humphrey, jumping to his feet, "I have over-stayed my welcome and I must get back to the office and write up my story for tomorrow's paper. You can rest assured, however, that the important details of this conversation will not get into print until you say the word. But remember, when the big scoop comes —it belongs to me!"
"I promise you that," returned Forrester, rising and extending his hand. "We'll shake hands on it."
"And you may count on me to help all I can in the meantime," declared Humphrey, as he grasped Forrester's hand.
"Let me offer you a suggestion for that article which is to appear tomorrow," said Forrester.
"Shoot!" replied Humphrey.
"Announce that I have given up all idea of fighting the 'Friends of the Poor,' and say that Saturday, before midnight, I shall place a package containing the money in that tree."
"I get you," smiled Humphrey. "I'll be there!"
CHAPTER IV – THE CAR IN THE FOG
Forrester glanced at his watch. It was just nine o'clock, not too late to make his promised call on the Nevins.
The Nevins' residence was on Dearborn Parkway, only a fifteen-minute walk for Forrester, so he sauntered west after leaving the house. A heavy mist was gathering on Lake Michigan and rolling through the streets before a gentle breeze from the east, completely shutting from view all but the nearest street lights and any pedestrians who might be abroad at this hour. Always a quiet neighborhood, the mist-hidden streets now seemed somber and deserted, and so still were his surroundings that Forrester's attention was presently attracted to the soft chug-chug of a motor somewhere in the fog behind him.
When the sound first caught his ear it had made little impression, but as the purring of the engine continued, apparently always at the same distance, it struck him as peculiar that the car did not catch up with and pass him. The threat which now hung over his head, as well as his recent interviews with detectives and the reporter from the Times, had made Forrester more alert than usual. He was keenly on the watch for anything that might appear out of the ordinary in character. Although he continued at the same pace without looking back, Forrester listened attentively to the sound of the motor and noted instantly that as he turned north on Dearborn Parkway, the motor followed him. He was convinced that he was under surveillance, and as detectives were not likely to keep guard over him from a motor car, it was clear that the persons who followed him had some other motive.
Forrester was well aware that auto bandits were active at all times in the city streets, and it was more than likely that a foggy night would prove especially inviting. Still, he could not recollect ever having heard of a hold-up of this character in his immediate neighborhood. As he deliberated on the matter, the suspicion grew stronger that the car which now followed him through the fog was connected in some way with the "Friends of the Poor." If that were so, there seemed little risk in allowing them to follow him, for it was certain that the ten thousand dollars they had demanded was of more importance to them at this time than his life, and as they had given him until midnight Saturday to pay the money, it did not appear likely that they would harm him before that time.
On the other hand, he realized that he had been especially active that day in taking steps to thwart them. It was not improbable that an organized band of this kind would have underground methods of gaining information and therefore might be familiar with everything he had done. Forrester recollected with a start that he had taken Humphrey for granted. Might it not be possible that Humphrey had merely been a spy sent to ascertain his attitude? As he recalled the young man's discourse it seemed strangely fanciful and might have been planned merely to add to his perplexities in seeking a solution. He had been extremely frank with Humphrey, and the supposed reporter would have a very comprehensive tale to unfold to his associates. Informed that Forrester planned to go further in his fight against them than any previous victim they had selected, was it not possible that they had decided to disregard his money, which might be easily replaced by a demand upon someone else, and make away with him before he had an opportunity to disrupt their plans? Forrester admitted to himself that he felt decidedly nervous and quickened his pace. He glanced back once or twice and saw the blurred but unmistakable outlines of a motor car without lights. Although the speed of the car had been slightly increased when he hastened his steps, the distance between them was maintained, and Forrester's mind grew easier as he became convinced that the sole purpose of the car behind him was to watch his movements. Very probably, he reflected, the "Friends of the Poor" kept track of their victims so that they could not escape by leaving the city or concealing themselves in some out-of-the-way place. Though he was probably safe for the moment, Forrester realized more fully now the dangerous nature of the task he had set himself.
By the time Forrester reached the Nevins home and rang the door-bell, the lesson had had its effect. He had acquired part of the attributes of a good detective – caution, and a suspicion of everybody and everything. In the future, so he assured himself, he would be more guarded in his conversation, not only with new acquaintances, but with his friends as well. At this moment a servant opened the door and Forrester stepped into the brilliantly lighted hallway with a feeling of relief.
As he was well known in this home he went immediately to the library without being announced. There he found his mother and sister with the Nevins family. Evidences of grief were apparent on all their faces and after a general exchange of subdued greetings, young Nevins led Forrester to a sofa in a corner and said, "I suppose you've heard about Father, Bob?"
"Yes," replied Forrester, "and I'm mighty sorry, old man. It must have been a great blow."
"It was a dreadful shock to Mother. You know when a person is ill, and death is momentarily expected, you are sort of prepared for the final end, but when you find your father dead on the front steps, and you know that he has been murdered, it is an awful stroke."
"If you don't mind talking about it, Charlie, I should like to hear some of the details."
"I