here we can run the 'Red Rover' in under
the trees, and where the boat cannot be seen from the lake on either
side of the island."

"You will have to change its color then. Why, in the sunlight you could
see that tub fifty miles away."

Harriet did not answer. She had rested on the oars, and was peering over
her right shoulder towards the thicket at the shore of the island.

"No, my dear, not where I am going to put the boat provided there is
room for it. Do you see that current swirling right into the island
there? I saw that from the deck of the 'Red Rover,' this morning, when
looking through the glasses. At least I thought it was a current. The
water everywhere else was very still, but a slight discoloration there,
as you see it, led me to believe there was a creek running into the
island."

"You have sharp eyes, Harriet. But where's your creek? I don't see it,"
laughed Jane.

"Neither do I. There may be no creek there, but if there is, it's going
to be a splendid place to hide."

"Hide?" wondered Jane.

"Yes."

"But why should we hide, darlin'?"

"In that way we may be able to get some clue to our unknown enemy,"
nodded Harriet. "If the boys did tow us over here, of course they'll
wonder what became of us."

"Do you think our enemy will try to find us?" asked Jane.

"Yes."

"I don't. We'll be wasting our time. The boys won't look for us, here,
either."

"Well, here is the creek, at any rate," exclaimed Harriet, swinging the
bow of the boat in as she spoke. "And oh, Jane! Look!"

A smooth sheet of dark water was revealed to the eyes of the girls. It
was shimmering in the deep shadow of the foliage under which it flowed
until it became lost in the shadows of foliage and rocks. Harriet drove
her boat in without the least hesitancy. She saw by glancing above her
head that there were no heavy limbs of trees hanging over the little
waterway. A sounding with the oar developed the fact that there was only
about three feet of water in the stream.

"Do you know where you are going, Harriet?" questioned Jane anxiously.

"No. But I don't care. Do you?"

"Not I. I can go where you go. Oh, look at that hole. It's a cave,
Harriet, and the stream goes right into it."

"I think you are mistaken, Jane. That looks to me more as if the water
had worn an opening in the rocks. The water must have been very high to
make such a large opening. Yes. See! The water swirls in at one side of
the opening and comes out on