"What were you and Ingua talking about for so long?" asked Mary Louise, when she and Josie were alone.  
"She was telling me her story," was the reply.
 
"All of it?"
 
"Every bit of it, I think."
 
"Oh, what was it all about?" questioned Mary Louise eagerly.
 
"I've promised not to tell."
 
"Not even me, Josie?"
 
"Not even you. Ingua insisted; and, really, dear, it's better you should know nothing just at present."
 
"Am I to be left out of all this thrilling mystery?" demanded Mary Louise with an aggrieved air.
 
"There won't be a thrill in it, until the end, and perhaps not then. But you shall come in at the finish, if not before; I'll promise that."
 
"Won't this enforced promise to Ingua tie your hands?" queried the other girl, thoughtfully.
 
"No. I didn't promise not to act, but only to keep the child's secret. For Ingua's sake, as well as to satisfy your curiosity—and my own—I'm going to delve to the bottom of Ned Joselyn's disappearance. That will involve the attempt to discover all about Old Swallowtail, who is a mystery all by himself. I shall call on you to help me, at times, Mary Louise, but you're not to be told what is weighing so heavily on poor Ingua's mind."
 
"Well," said Mary Louise, "if I may help, that will serve to relieve my disappointment to an extent. But I'm surprised at Ingua. I thought she loved and trusted me."
 
"So she does," asserted Josie. "Since I've heard the story, I'm not surprised at Ingua at all. If you knew all, my dear, you would realize why she believes that one confidant is enough. Indeed, I'm rather surprised that Ingua ventured to confide in me."
 
"Is it so serious, then?"
 
"If her fears are justified," replied Josie gravely, "it is very serious."
 
"But are they justified?" urged Mary Louise.
 
"Ingua is a child, and very sensitive to impressions. But she is a shrewd child and, living a lonely life, has had ample time to consider the problems that confront her. Whether she is right or wrong in her conjectures, time will determine. But don't question me further, please, or you will embarrass me. To-morrow I want to go to the city, which is the county seat. Will you go with me? And can we get Uncle Eben to drive us over in the car?"
 
"I'll ask Gran'pa Jim."
 
Colonel Hathaway was rather amused at the efforts of the two girls to fathom the mystery of Old Swallowtail, but he was willing to assist in any practical way. So Uncle Eben drove them to the county seat next day and Josie spent several hours in the county clerk's office and paid a visit to the chief of police, who knew her father, John O'Gorman, by reputation. Mary Louise shopped leisurely while her friend was busy with her investigations and at last they started for home, where they arrived in time for dinner. On the way, Mary Louise inquired if Josie had secured any information of importance.
 
"A little," said the girl detective. "For one thing, old Hezekiah Cragg pays taxes on just one bit of land besides that little homestead of his. It is a five-acre tract, but the assessment puts it at an astonishingly low valuation—scarcely ten per cent of the value of all surrounding property. That strikes me as queer. I've got the plat of it and to-morrow we will look it up."
 
They found it was not easy to locate that five acres, even with a map, when the two girls made the attempt the next forenoon. But finally, at the end of a lonely lane about a mile and a half from the village, they came upon a stony tract hemmed in by low hills, which seemed to fit the location described. The place was one mass of tumbled rocks. Little herbiage of any sort grew there and its low assessment value was easily explained. The surrounding farms, all highly cultivated, backed up to the little waste valley, which was fenced out—or rather in—by the owners of the fertile lands. One faintly trodden path led from the bars of the lane the girls were in toward Mr. Cragg's five acres of stones, but amid the jumble of rocks it would be difficult to walk at all.
 
"This is an odd freak of nature," remarked Josie, gazing at the waste with a puzzled expression. "It is easy to understand why Mr. Cragg hasn't sold this lot, as he did all his other land. No one would buy it."
 
"Haven't the stones a value, for building or something?" asked Mary Louise.
 
"Not in this location, so far from a railway. In my judgment the tract is absolutely worthless. I wonder that so economical a man as Mr. Cragg pays taxes on it."
 
They went no farther than the edge of the rock-strewn field, for there was nothing more to see. Up ............