"What is it?" asked Betty, eagerly.

"I thought you might be interested," said the young man, "and that is why I called at your house," and he nodded to Will.

"You had gone out," remarked Will to Grace, "so I asked dad where, as the maid said you'd all been in the library. Then I called up here," and he nodded to Amy.

"Glad you did," she returned. She seemed to have forgotten the trouble of the afternoon.

"Well," went on Mr. Blackford, "I feared it was a sort of imposition to come, and----"

"I told him it wasn't at all," interrupted Will.

"So on I came," proceeded the young business man.

"But what is the clue?" asked Grace, interestedly.

"This," was the reply, as he took some papers from his pocket. "But it's a clue that----"

"Isn't a clue," put in Will.

"Because----"

"It breaks off in the middle."

"Oh, Will, let him tell it; can't you?" demanded Grace, impatiently. "We don't know whom we're listening to."

"Well, to be brief," said Mr. Blackford, "the firm I have engaged, the other day, wrote me that they were on the track of my sister. They felt sure they were going to find her, and I was very hopeful.

"It seems that they had found some old doc.u.ments in the attic of a house where some distant relatives live. They wrote me they were sending them on, and--here they are!"

He brought out a bundle of time-stained and yellow papers, and spread them on the table.

"Gracious!" cried Will. "Your sister must be quite elderly to have such ancient doc.u.ments refer to her."

"No," said Mr. Blackford, "she is younger than I am, I believe. But I have no certain knowledge of that. Anyhow, this is part of a letter written about the girl whom I have every reason to believe is my sister.

And the part that is most interesting----"

"Is where----" began Will.

"Can't you keep still?" begged his sister.

"Has 'oo dot any tandy?" and he imitated little Dodo.

"Oh, take that!" and Grace pa.s.sed him a caramel. "Now, let's hear what it is, Mr. Blackford."

"There is a part of the letter which says this," went on Mr. Blackford, and he proceeded to read:

"'You can always identify the girl because she has a most peculiar birth-mark on----'"

He ceased reading.

"Well, go on, please," requested Betty. "This is getting interesting."

"It isn't _getting_ interesting--it's so already," declared Mollie. "Go on, please, Mr. Blackford, tell us what sort of birth-mark your sister has."

"That's just the trouble," he remarked, ruefully. "I can't do it."

"Why not?" Betty wanted to know.

"Because, just at that point--where the description of the birth-mark, and its location, should appear--the letter is torn. A corner is gone.

I have no more idea of what sort of identifying mark my sister has, than have you. It is worse than before, for I saw hope ahead of me, only to see it disappear now.

"I feel sure that the girl referred to in the old letter is my sister; but how can I identify her, in case I meet her, until I know what sort of a mark she has, and where it is?"

"You can't!" declared Will, positively.

"And that makes it all the more tantalizing," went on Mr. Blackford.

"They even--that firm I spoke of--they even had located the part of the country where it might be possible my sister was, and now to have it fail this way----"

"Where did they say she might be?" asked Amy.

"Somewhere up in Canada. But it is rather vague. If only that piece was not torn off the edge of the letter!"

"Can't you find it somewhere?" asked Mollie. "Maybe in forwarding it the people you hired tore it by accident."

"I thought of that, so I telephoned as soon as I got this letter, asking where the missing piece was. I got word back that they knew nothing about it."

There was silence for a moment, while they all looked at the mutilated doc.u.ment Mr. Blackford held up. It showed a tear across one corner, a tear that disposed of the most vital piece of information contained on the whole paper.

"That's too bad," spoke Amy, sympathetically.

"Yes," agreed Mollie, as she put back a stray and rebellious lock of hair, "it spoils all your plans, I suppose, Mr. Blackford."

"In a way, yes. But I'm not going to give up. I'm going to find out where they got this doc.u.ment from, and go there. It may have been in some old attic trunk, among some--love letters--and the missing piece may be there."

"Without it you're all at sea," declared Will. "You don't know what sort of a mark to look for, nor where it might be."

"And he can't very well go around asking all the girls he meets if they have peculiar birth-marks," commented Mollie.

"Well, I hardly know why I told you my troubles," said the young man, "but----"

"Why shouldn't you?" asked Betty, pleasantly. "We are interested in you, of course, ever since----"

"That five hundred dollar bill you thought was gone for good," added Amy. "But if we hear of anything----" and she paused suggestively.

"I wish you'd let me know!" exclaimed Mr. Blackford. "I know you girls are very lucky. You've proved it several times. Now if you happen to hear of anyone who would fit what description I have of my sister--and it isn't much, to tell the truth--or if you think you see anyone who resembles me, or who has a peculiar birth-mark, just let me know. You travel around so much, and you meet so many strange people----"

"We do seem to," agreed Grace.