"Ah-ha!" cried Green. "_Now_ you’ve got the idea! These fellows have a headquarters somewhere. After they kill a guy they bring him out in an automobile and throw him alongside the road somewhere. The thing to be done now is to locate their headquarters. _That’s_ what little Benny is goin’ to do!" "How do you propose to find that out?" inquired Forrester. "Watch the tree and follow ’em!" replied Green, decisively. "That sounds all right," objected Forrester, "but the police have been watching that tree for months without getting sight or sound of anyone." "Leave it to _me_," assured Green, with a wide sweep of his hand. "I know things these here city dicks never think about. Now, Mister—Mister—, by the way, you ain’t told me your name yet." Forrester handed his card to Green. "Now, Mr. Forrester," continued Green, as he glanced at the card, "take my advice and don’t let nobody bunco you into any strange place. And I wouldn’t take no rides in strange automobiles, either. I’ll let you hear from me in a couple o’ days. In the meantime you can count on findin’ me around that tree o’ nights. I kinda got an idea that there tree’s a mighty busy place these nights. The ’Friends o’ the Poor’ seem to be makin’ a big drive right now. I suppose you heard about the banker, Nevins, today?" "Yes," said Forrester, rising to go. "I shall probably have full details of that shortly. My sister is engaged to Mr. Nevins’ son." "Ah-h-h!" sighed Green again, as his new client passed out of the door. CHAPTER III—ENGINEERING-CRIMINOLOGY Although the yearly hegira from town to suburb was well on, the Forresters had delayed their departure and were still residing in the town house on Bellevue Place. To a man of Forrester’s active disposition Bellevue Place meant a comparatively easy walk from the downtown section. Moreover, in the present troubled condition of his mind, the exercise would be conducive to clearer thinking, so he started out with the intention of walking home. As he was crossing the Michigan Avenue bridge over the Chicago River, a motor car slowed up by the curb and Forrester heard someone call to him. Glancing around, he saw that it was Prentice. "On your way home?" inquired Prentice. Forrester answered in the affirmative. "Then jump in with me," said Prentice. "Thanks," returned Forrester, "but I had decided to walk home." "Better change your mind," urged Prentice. "It’s a fairly long walk, and I should like your company. Remember that after you leave me I have a long and lonesome drive." "You are out on the North Shore now, are you?" queried Forrester, as he climbed into the car. "Yes," answered Prentice. "We closed the town house on the first. I’m surprised that your folks are still in the city." "We hope to leave soon. The decorators are still busy at our place. We gave ’Woodmere’ a good overhauling this spring. I should think you would rather take the train than have such a long drive when you are alone."