We got into the motor boat and followed her, and, except for a most unjust sense of irritation that I had not drowned myself by following her in the canoe, she was unharmed.  We got her into the motor boat and into a blanket, and Aggie gave her some blackberry cordial at once.  It was some time before her teeth ceased chattering so she could speak.  When she did it was to announce that she had made a discovery.

“He’s a spy, all right!” she said.  “And that Indian is another.  Neither of them saw me as I floated past.  They were on Island Eleven.  Mr. McDonald wrote something and gave it to the Indian.  It wasn’t a letter or he’d have sent it by the boat.  He didn’t even put it in an envelope, so far as I could see.  It’s probably in cipher.”

Well, we took her home, and she had a boiled egg at dinner.

The rest of us had fish.  It is one of Tish’s theories that fish should only be captured for food, and that all fish caught must be eaten.  I do not know when I have seen fish come as easy.  Perhaps it was the worms, which had grown both long and fat, so that one was too much for a hook; and we cut them with scissors, like tape or ribbon.  Aggie and I finally got so sick of fish that while Tish’s head was turned we dropped in our lines without bait.  But, even at that, Aggie, reeling in her line to go home, caught a three-pound bass through the gills and could not shake it off.

We tried to persuade Tish to lie down that afternoon, but she refused.

“I’m not sick,” she said, “even if you two idiots did try to drown me.  And I’m on the track of something.  If that was a letter, why didn’t he send it by the boat?”

Just then her eye fell on the flagpole, and we followed her horrified gaze.  The flag had been neatly cut away!

Tish’s eyes narrowed.  She looked positively dangerous; and within five minutes she had cut another flag out of the back breadth of the petticoat and flung it defiantly in the air.  Who had cut away the signal—­McDonald or the detective?  We had planned to investigate the nameless lake that afternoon, Tish being like Colonel Roosevelt in her thirst for information, as well as in the grim pugnacity that is her dominant characteristic; but at the last minute she decided not to go.

“You and Aggie go, Lizzie,” she said.  “I’ve got something on hand.”

“Tish!” Aggie wailed.  “You’ll drown yourself or something.”

“Don’t be a fool!” Tish snapped.  “There’s a portage, but you and Lizzie can carry the canoe across on your heads.  I’ve seen pictures of it.  It’s easy.  And keep your eyes open for a wireless outfit.  There’s one about, that’s sure!”

“Lots of good it will do to keep our eyes open,” I said with some bitterness, “with our heads inside the canoe!”

We finally started and Hutchins went with us.  It was Hutchins, too, who voiced the way we all felt when we had crossed the river and were preparing for what she called the portage.