Meanwhile the captain reseated himself, but more carefully.  He had a plan or method of procedure to think out, or so it seemed, for he sat a long time in rigid immobility, with only the scowl of perplexity or ill-temper on his brow to show the nature of his thoughts.  Then he drew a sheet of paper toward him, and began to write a letter.  He was so absorbed over this letter and the manipulation of it, having but one hand to work with, that Sweetwater determined upon a hazardous stroke.  The little book which the captain had consulted, and which had undoubtedly furnished him with a key to those two incongruous words, lay on the floor not far from him, having been flung from its owner’s hand during the moments of passion and suffering I have above mentioned.  To reach this book with his foot, to draw it toward him, and, finally, to get hold of it with his hand, was not difficult for one who aspired to be a detective, and had already done some good work in that direction.  But it was harder to turn the leaves and find the words he sought without attracting the attention of his fierce companion.  He, however, succeeded in doing this at last, the long list of words he found on every page being arranged alphabetically.  It was a private code for telegraphic or cable messages, and he soon found that “Happenings” meant:  “Our little game discovered; play straight until I give you the wink.”  And that “Afghanistan” stood for:  “Hush money.”  As the latter was followed by the figures I have mentioned, the purport of the message needed no explanation, but the word “Frederick” did.  So he searched for that, only to find that it was not in the book.  There was but one conclusion to draw.  This name was perfectly well known between them, and was that of the person, no doubt, who laid claim to the two thousand dollars.

Satisfied at holding this clew to the riddle, he dropped the book again at his side and skilfully kicked it far out into the room.  Captain Wattles had seen nothing.  He was a man who took in only one thing at a time.

The penning of that letter went on laboriously.  It took so long that Sweetwater dozed, or pretended to, and when it was at last done, the clock on the mantelpiece had struck two.

“Halloo there, now!” suddenly shouted the captain, turning on the messenger.  “Are you ready for another journey?”

“That depends,” smiled Sweetwater, rising sleepily and advancing.  “Haven’t got over the last one yet, and would rather sleep than start out again.”

“Oh, you want pay?  Well, you’ll get that fast enough if you succeed in your mission.  This letter” he shook it with an impatient hand—­“should be worth two thousand five hundred dollars to me.  If you bring me back that money or its equivalent within twenty-four hours, I will give you a clean hundred of it.  Good enough pay, I take it, for five hours’ journey.  Better than sleep, eh?  Besides, you can doze on the cars.”

Sweetwater agreed with him in all these assertions.  Putting on his cap, he reached for the letter.  He didn’t like being made an instrument for blackmail, but he was curious to see to whom he was about to be sent.  But the captain had grown suddenly wary.