“Settled back comfortably”—­yes, but only for a short time.  Marion never before in her life received two such letters.  Both were anonymous.  The first one that she opened aroused enough curiosity to “unsettle” her.  She thought she knew whom it was from—­those ingenious Boy Scouts of Spring Lake—­perhaps it was written by cousin Clifford himself.  It was just like him.  He was a natural leader among boys, and often up to mischief of some sort.  Marion was sure he was one of the prime movers of the Scout invasion of Hiawatha Institute.

But the next letter was the real thriller, or rather cold chiller.  She knew very well what it meant.  From the point of view of the writer it meant “business,” a threat well calculated to work terror in her own heart and the heart of every other member of Flamingo Fire.  It was a threat couched in direful words, warning her and her friends not to go to Hollyhill on their charity mission, as announced, and predicting serious injury if not death to some of them.  It was signed with a skull and cross-bones.

* * * * *

CHAPTER IV.

Studying the mystery.

Is there any wonder that Marion Stanlock, after reading letter No. 2 was seriously in doubt as to whether No. 1 was from the Scouts who had promised another surprise for the Camp Fire Girls in the near future?  Judge for yourself—­here is No. 1: 

Something Doing Soon
Look Out
something doing soon
look out
=something doing soon
look out!=

That was all.  The second letter read thus: 

“Miss Stanlock:  This is to serve you with warning not to take your friends with you to Hollyhill this vacation to work among the poor families of the striking miners.  We know that move of yours is inspired by the rankest hypocrisy, that you have no genuine desire to do anything for our starving families.  This move of yours, we know, was planned by that villainous father of yours to cloud the big issue of our fight.  If you do carry out your plans, some of you are liable to get hurt, and it need not surprise anybody if some of you never get back to Westmoreland alive.

    Go Slow!  Be Careful!  Look Out!”

Marion was not easily panic-stricken, but it is of the nature of a truism to say that this letter applied the severest test to her nerves.  That the writer was in deep earnest she had no reason to doubt.  She had read of so many crimes preceded by threatening letters of this sort that the suggestion did not come to her to regard this one lightly.  Although there was no common basis for comparing the handwriting of the two missives, one being lettered in Roman capitals and the other in ordinary script, nevertheless she quickly dismissed the first suspicion that letter No. 1 was written by Clifford Long or some other Scout of Spring Lake academy.  Both ended with the words “Look Out.”  Plainly this was a result of carelessness on the part of the writer.  Evidently he had planned to cause her to believe that the two letters were written by different persons, for he had taken the pains of differentiating the superscriptions on the envelopes as well as the contents within.