"Look out," yelled Ted, for the black slimy thing dangling on Nancy's line seemed to be making directly for her face, as it swung back and forth and darted violently toward the shore. "Oh-h-h-h-h!" Nancy screamed. "He's going for--" But she was taking no further chances, instead, she flung her pole, line and hook and catch, as far from her as a single fling could send it. The pole floated contentedly but the slimy thing was again hidden in its beloved waters, although it must have still been impaled upon the tortuous hook. Ted looked a moment at the lost outfit. "Nancy," he said gloomily. "You're crazy. That was a fine, fat eel, and they're hard to catch that way. And look at--your--pole." "I'll get it," decided the surprised girl, instantly slipping down from the log and leaning out over the stream. "Don't!" yelled Ted. But the warning was given too late, for as Nancy stepped on what seemed to be grass, she found herself thrust into the water, deep enough to frighten her of something worse than a snake. "Oh!" she yelled again. "I've got to swim out, I'll smother in the bog if--I--don't." And so saying she flung her body free from the deep marsh-grass, and struck out in an emergency stroke toward the open stream. "Go up to the cove!" Ted yelled. "Just around that pine tree! I'll meet you there!" The light clothing she wore was not much more cumbersome than some bathing suits are often found to be, so that Nancy, a capable swimmer, was now pulling surely toward the cove, while Ted was racing, as best he could in the heavy undergrowth to meet her as she would land. But just as Nancy turned in to a clear little corner to make her landing, she heard a muffled call. "Help! Help!" came the indistinct cry. Ted was abreast of her and he too heard the call. "It's over in the sand dunes," he yelled, as Nancy stepped ashore and shook some of the heavy water from her clothing. "Quick, Nancy, the fellows went to play Indian there!" CHAPTER XVII THE CAVE-IN There was no time to think of wet garments as Nancy raced after Ted toward the sand dunes. "Quick," he urged. "They're the little fellows, Billy and Jack, and they must be under the sand." Just beyond the trees and undergrowth that surrounds Oak's Pond, a stretch of sand hills offered the youngsters an ideal playground. A few scrubby pines managed to draw from the dry soil enough vitality for a very much impoverished growth, and it was from the direction of the trees that the feeble call was now heard, at protracted intervals. "There!" pointed out Ted. "There's the shack. They must be in a cave-in near it." His surmise proved correct, for quickly as brother and sister could reach the spot, they found every evidence of a cave-in and a sand deluge. "We're here," Ted called. "That you Billy?" "Oh, yeah," came a pitiful little squeak. "We're smoth-rin' to death. Quick--please--quick."