Before Helen had picked her up on the road to the Red Mill that first day, Ruth had never ridden in a motor car.  On that occasion they had traveled very slowly, while the girls talked.  But now, when she was seated beside her new friend, Helen ran the auto on its high gear, and they shot away up the level river road at a pace that almost took Ruth’s breath away,

“Up here among the foothills is the big Minturn Pond Dam,” Tom said, leaning forward to speak to their guest.  “It’s twenty miles above your uncle’s dam and is a deal bigger.  And some say it is not safe—­ Wait, Nell!  Slow down so that we can see the face of the dam from the Overlook.”

The speed of the car was immediately reduced under Helen’s manipulation, and then she swerved it into a short side road running toward the river, and they came out upon a little graveled plaza in the center of a tiny park, which gave a splendid view of the valley in both directions.

But the young people in the motor car turned their eyes to the west.  There the face of the Minturn dam could be discerned; and even as they looked at it they seemed to see it changing—­ dissolving, covered with mist, and spouting geysers of what at first seemed like smoke.  But it was Tom who realized the truth.

“She’s burst!” he cried.  “The old dam’s burst!  There she goes in a dozen places!”

Although they were several miles down the valley, the thunder of the bursting masonry now echoed in their ears.  And up from the bottom of the wall, near its center, a great geyser spouted.  In a moment the wall crumbled and they saw tons upon tons of the masonry melt away.  The waters of the pond burst through in a solid flood and charged down the valley, spreading wider and wider as it charged on, and bearing upon its crest every light and unstable structure found in its path.

It was a startling—­ a terrifying sight.  No wonder the two girls cried out in alarm and clung together.  The sight of the charging flood fascinated them.

But then they were aroused—­ and that within the first half minute of their terror—­ by Tom.  He was trying, crippled as he was, to climb over into their seat.

“What are you doing, you foolish boy?” cried Helen.  “Sit down.”

“We’ve got to get out of here!” muttered the excited youth.

“Why, we are safe here.  The water will never rise to this height.”

“I know it!  I know it!” groaned Tom, falling back in his seat and paling because of the pain from his arm, which he had twisted.  “But don’t you see?  There are many down the valley who won’t know of this until too late.  Why, they can’t see it at the bridge—­ at Culm Falls—­ until the flood is right upon them.”

“It’s true!” gasped Helen.  “What shall we do?”

“We must warn them—­ we can warn them, can’t we?” demanded Ruth.  “This car runs so fast—­ you control it so well, Helen.  Can’t we warn them?”