His gaze swept across the prairie to where, half a mile away, a bunch of Shoe-Bar cattle grazed peacefully. If this sick beast should get amongst them, the yearlings at least, to whom the disease is fatal, would be dying like flies in twenty-four hours. Buck glanced back at the steer again, and as he noted the T-T brand, his face hardened and he began taking down his rope. "The hellions!" he grated, an angry flush darkening his tan. "They ought to be strung up." The animal started to move away, and Buck lost no time in roping him. Then he turned his horse and urged him toward the fence, dragging the reluctant brute behind. Fortunately he had his pliers in the saddle-pocket, and, taking down the wires, he forced the creature through and headed for a deep gully the mouth of which lay a few hundred yards to the left. Penetrating into this as far as he was able, he took out his Colt and deliberately shot the steer through the head. And if Kreeger or Siegrist had been present at that moment, he was furious enough to treat either of them in the same way without a particle of compunction. "Hanging would be too good for them, the dirty beasts!" he grated. The thing had been so fiendishly cold-blooded and calculating that it made his blood boil, for it was perfectly evident now to Buck that he had thwarted a deliberate plot to introduce the blackleg scourge among the Shoe-Bar cattle. Instead of riding fence, the two punchers must have made their roundabout way immediately to the stricken T-T ranch, secured in some manner an infected yearling and brought it back through the twisting mountain trail Bud had spoken of a few days before. Lynch's was the directing spirit, of course; for none of the others would dare act save under his orders. But what was his object? What could he possibly hope to gain by such a thing? Buck could understand a man allowing rustlers to loot a ranch, if the same individual were in with them secretly and shared the plunder. But there was no profit in this for anyone--only an infinite amount of trouble and worry and extra work for them all, to say nothing of great financial loss to--Mary Thorne. When Stratton had secured his rope and rode back to the Shoe-Bar pasture, his face was thoughtful. He was thinking of those excellent offers for the outfit Miss Thorne had lately spoken of, which Lynch was so anxious for her to accept. Could the foreman's plotting be for the purpose of forcing her to sell? From something she had let fall, Buck guessed that she was more or less dependent on the income from the ranch, and if this failed she might no longer be able to hold the property.