Green's sudden departure, following the enforced and trying separation from Mary Sturtevant, depressed Forrester and left him with a sense of helpless loneliness. He ate dinner that night in a morose silence that called forth several cutting remarks from Josephine. After dinner Forrester sought the seclusion of his room in preference to the library. He wanted to be isolated in order to work out his problem, for Green's words, coupled with the afternoon visit to Lucy, had aroused a determination to end the suspense quickly and finally. He had information that was unknown to the police—information which Green claimed to be vital—and he wanted to decide how to use it to the best advantage.

Green's intimation that Mary Sturtevant might not be an actual criminal gave a different twist to the situation. To conceive of her being a bandit queen had seemed preposterous, yet what other construction could be placed on her actions?

But Forrester also recalled Prentice's vague reference to a new angle in the case—a phase that had hitherto not been thought of. "Something of world-wide significance," were his words. What connection could there be between these local, cold-blooded murders and the rest of the world?

Unexpectedly a great light seemed to come—swift, overwhelming, terrific in its magnitude. Forrester caught his breath.

Red interests!

Why not? Was not the long arm of Bolshevism reaching out everywhere in an effort to destroy nations and bring about a new order of things; could not some master mind have devised, with grim humor, a plan to make so-called Capitalism pay the cost of its own destruction? Forrester's head swam with these thoughts. He saw now that the savage reprisals for refusal to pay could not possibly be the work of ordinary men. Not even the most desperate criminal would take the risk of so arousing public wrath. On the other hand, would not the wholesale fear aroused among wealthy men by this method be part of Red propaganda?

How many perplexing things seemed to assume a new and easily explained meaning. "Friend of the POOR"—an appropriate title seen from the viewpoint of Red schemers. Lucy, a woman close to the soil, her color a bar to progress, despite her education, would be an easy convert. Forrester was sure the mystery embraced her at some point, yet Green had said she could not resist the temptation of displaying her prosperity. But working fanatically for what she believed a great cause, would explain it. It was possible that she was the one who collected the money and passed it on.

And Mary Sturtevant's part became less blameworthy. Many women of her class had dabbled in amateur Bolshevism. In her case she had, perhaps, gone a little too far, and the Red tentacles were reaching out and seeking to draw her closer. Probably she was making a brave struggle to free herself and hoping at any moment to win.

But at what point could he begin his attack in the light of this new development? There must be something more tangible than theories and fanciful ideas to lay before the police. The responsibility must be laid upon some one, with facts to back up the accusation. Forrester thought of Humphrey and his triangulation theory. It seemed as whimsical as tossing a coin, but Forrester decided to try.

Taking a pad and pencil he first placed a small circle for the oak tree. His recent speculative conclusions led him to draw a small square for Lucy's cottage in its approximate position near the tree. Obviously, Mary Sturtevant was the next most prominent figure in the case, and with a mental measurement of the probable location of the house she occupied, he drew another square. The connecting of these three points with lines astounded Forrester. He saw that he had an obtuse-angled triangle, with Lucy occupying the controlling point.

However, there must be one or more additional triangles that would overlap, for Humphrey, in explaining his theory, had said: "At some point the lines will cross."

Forrester mused over this for a time. He could not decide on other points which would be near enough to these to form an overlapping triangle. He tried several ideas without result. His own home was too far away. But how about other victims? Suddenly it came to him. The first and last victims, so far as he knew, were Prentice and Melville, and the homes of these were reasonably near. So Forrester placed a square for each of these men's homes on his sketch. That still left a third point for his triangle. He finally decided to use the tree again for this point. The lines did not cross, at least in the way he imagined Humphrey had in mind, but they did serve to increase the size of his original triangle and bring it to a perfect form of the isosceles triangle. It was significant, moreover, that the line from Prentice, the first victim, led directly through Lucy's cottage to the tree, and he noted with a start that the line from the Melville home, where the girl had been deeply involved, led through Mary Sturtevant's house.

This is the rough sketch as Forrester completed it:

The way to a solution unquestionably led through Lucy and Mary Sturtevant, if there were anything at all to Humphrey's idea. Green pointed at the girl. Forrester's inclinations led him to the negress, and the odd working out of the triangle theory seemed to confirm him in his impressions. Forrester decided to investigate Lucy at once. His reference to the police had amused instead of angered her. She had pithily expressed her disdain of them. Was it not possible that these feelings arose from a sense of victory? In searching her house, the police had failed to find something that she knew was there! Whatever it was, Forrester intended to locate it, and use his information for what it might be worth.

Forrester took an electric pocket lamp from the top of his chiffonier, and a dark muffler from a drawer. These he placed in his pocket. Then he selected a cap of an unobtrusive shade and went down to the laundry. There he cut off a short length of clothesline, wound it around his body and buttoned up his coat.

Unlocking the laundry door, which opened at the southern end of the house, Forrester looked carefully around. He could hear William whistling at his work in the garage, while above him his sister was playing the piano in the music room. No other sound reached him and no one was in sight. Forrester closed the laundry door softly and stole across the lawn to the road.