"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?"

"Try it, Sis!" shouted Tom. "You can do it!"

And already his sister, setting her teeth hard upon her lower lip, was
backing and turning the motor car. In twenty seconds they were dashing
off upon the track over which they had so recently come-- on the road
down the valley with the flood following fast behind them.

CHAPTER X

THE RACE

The two girls on the front seat of the flying automobile were not
prepared for racing. Of course, Ruth Fielding had no proper automobile
outfit, and Helen had not expected such an emergency when she had
started with her crippled brother for this afternoon run. She had no
goggles, nor any mask; but she had the presence of mind to raise the
wind-shield.

Already they could have heard the steady roaring of the advancing
flood had not the racing motor car drowned all other sounds. There
was, however, no need to look behind; they knew the wave was there and
that it was sweeping down the valley of the Lumano with frightful
velocity.

Indeed, they were not at all sure for those first few miles whether
they were traveling as fast as the flood, or not. Suppose the wave