“It was the extractor that made me suspicious,” she finished.  “What were you going to extract?  Teeth?”

“And so, when my Indian was swimming, you went through his things!  It’s the most astounding thing I ever—­My dear lady, an extractor is used to get the hooks out of fish.  It was no cipher, I assure you.  I needed an extractor and I ordered it.  The cipher you speak of is only a remarkable coincidence.”

“Huh!” said Tish.  “And the paper you dropped in the train—­was that a coincidence?”

“That’s not my secret,” he said, and turned sulky at once.

“Don’t tell me,” Tish said triumphantly, “that any young man comes here absolutely alone without a purpose!”

“I had a purpose, all right; but it was not to blow up a railroad train.”

Apparently he thought he had said too much, for he relapsed into silence after that, with an occasional muttering.

It was eight o’clock when Hutchins’s canoe came into sight.  She was paddling easily, but the detective was far behind and moving slowly.

She saw the camp with its uninvited guests, and then she saw us.  The detective, however, showed no curiosity; and we could see that he made for his landing and stumbled exhaustedly up the bank.  Hutchins drew up beside us.  “He’ll not try that again, I think,” she said in her crisp voice.  “He’s out of training.  He panted like a motor launch.  Who are our visitors?”

Here her eyes fell on Mr. McDonald and her face set in the dusk.

“You’ll have to go back and get some gasoline, Hutchins.”

“What made you start out without looking?”

“And send the vandals away.  If they wait until I arrive, I’ll be likely to do them some harm.  I have never been so outraged.”

“Let me go for gasoline in the canoe,” said Mr. McDonald.  He leaned over the thwart and addressed Hutchins.  “You’re worn out,” he said.  “I promise to come back and be a perfectly well-behaved prisoner again.”

“Thanks, no.”

“I’m wet.  The exercise will warm me.”

“Is it possible,” she said in a withering tone that was lost on us at the time, “that you brought no dumb-bells with you?”

If we had had any doubts they should have been settled then; but we never suspected.  It is incredible, looking back.

The dusk was falling and I am not certain of what followed.  It was, however, something like this:  Mr. McDonald muttered something angrily and made a motion to get into the canoe.  Hutchins replied that she would not have help from him if she died for it.  The next thing we knew she was in the launch and the canoe was floating off on the current.  Aggie squealed; and Mr. McDonald, instead of swimming after the thing, merely folded his arms and looked at it.

“You know,” he said to Hutchins, “you have so unpleasant a disposition that somebody we both know of is better off than he thinks he is!”