As the boy looked on, his father glanced up suddenly and caught sight of the anxiety mirrored in his face. The man smiled kindly. "I can find no answer to this riddle, Don," he said. "Listen! Perhaps you can help me. A few days ago I received word from Crescent Ranch that Johnson, our manager, had been thrown from his horse while out on the range and so badly hurt that he will never again be able to continue his work with us. They have taken him to the hospital at Glen City. The letter came from Tom Thornton, the head herder at the ranch. Thornton assured me that everything was going well, and that there was not the slightest need for me to come to Idaho." Donald listened. "Well, to-day I received this telegram. It is neither from Johnson nor Thornton. It reads: "'You would do well to visit Crescent Ranch,' and it is signed--'Sandy McCulloch.'" "Who is Sandy McCulloch?" asked Donald. "That's the puzzle! I do not know. I never heard of any such person in my life--not that I remember. Evidently, though, he knows enough about me to know that I own that sheep ranch, and to think that I ought to go out there and see it. I do not understand it at all. What do you make of it, son?" Donald thought carefully. "Do you suppose anything is wrong on the ranch?" "No, indeed! Thornton wrote particularly that everything was all right. He was Johnson's assistant, and he ought to know. Besides, he has been with us a long time, and is thoroughly familiar with every part of the work." "Maybe it's a joke," ventured Donald. "It would be a stupid sort of joke to get me from Boston to Idaho on a wild-goose chase. No, there is no joke about this," went on Mr. Clark, rising and pacing the floor. "Sandy McCulloch is real, and he has some real reason for wanting me to go to Crescent Ranch. I think I shall take his advice and go." Donald was astounded. His father never left home. "And the office?" "Uncle Harold will have to do double duty while I am gone." "And--and--I?" inquired the boy hesitatingly. Idaho seemed very far away--quite at the other end of the world. "You? Oh, you'll have to go along too! I shall need you." Donald drew a long breath. "Let me see," continued his father, "this is the end of March, isn't it? Your spring term is about over. I happen to know you are well up in your work, for I met Mr. Hurlbert, the high school principal, only yesterday. I am sure that if you fall behind by going on this trip you will study all the harder to make up the work when you get back, won't you?" "Yes, sir!" was the emphatic promise. "You see I've no idea how long I shall be detained out West, therefore I have no mind to leave you here. You might be ill. Besides, I should miss you, Don." "I'd much rather go with you, father." A quick light of pleasure flashed in the father's eyes.