"Oh, dear!" sighed Betty, when they had exhausted all possibilities, "I did hope that money mystery was going to be solved. Now it's as far off as ever. But I'll keep this torn piece of letter for evidence. Poor fellow! He may have built great hopes on that five hundred dollar bill--then to lose it!" They went to the house of Amy's cousin in Middleville. There they spent an enjoyable evening, meeting some friends who had been invited in. Amy said nothing about the disclosure to her of the strange incident in her life. Probably, she reflected, her relative already knew it. Morning saw them on the move again, with Broxton, where a married sister of Grace lived, as their objective point. The day was cloudy, but it did not seem that it would rain, at least before night. And even the frown of the weather did not detract from the happiness of the chums. They laughed and talked as they walked on, making merry by the way. Stopping in a country store to make sure of their route they were informed that by taking to the railroad track for a short distance they could save considerable time. "Then we ought to do it," decided Betty, "for we don't want to get caught in the rain," and she glanced up at the clouds that were now more threatening. They reached the railroad track a short distance out of the little village, and proceeded down the stretch of rails. "There's a train in half an hour," a man informed them, "but you'll be off long before then." "I hope so," murmured Amy. They had nearly reached the end of the ballasted way, when Betty, who was in the lead, came to a sudden halt. "What is it," asked Mollie, "a snake? Oh, girls!" "No, not a snake," was the quick answer. "But look! This rail is broken! It must have cracked when the last train passed. And another one--an express--is due soon! If it runs over that broken rail it may be wrecked! Girls, we've got to stop that train!" and she faced her chums resolutely. CHAPTER XV "IT'S A BEAR!" "What can we do?" It was Grace who asked the question. It was Betty, the Little Captain, who answered it. "We must stop the train," she said. "We must wave something red at it. Red always means danger." "Mollie's tie," exclaimed Amy. Mollie was wearing a bright vermilion scarf knotted about the collar of her blouse. "It isn't big enough," decided Betty. "But we must do something. That man said the train would come along soon. It's an express. A slow train might not go off the track, as the break is only a small one. But the express--" She paused suggestively--apprehensively. "There's a man!" cried Grace. "A track-walker!" cried Betty. "Oh, he'll know what to do," and she darted toward a man just appearing around the curve--a man with a sledge, and long-handled wrench over his shoulder. "Hey! Hey!" Betty called. "Come here. There's a broken rail!" The man broke into a run. "What's that?" he called. "Got your foot caught in a rail? It's a frog--a switch that you mean. Take off your shoe!"