Ned took a thin, flat steel key from his pocket and held it out to the Captain. It was a key of peculiar construction, evidently made of individual pattern. In fact, it was such a key as usually goes with a strong cash box, having no duplicate.
"This was not used to open the suitcase?" he asked.
"Certainly not," was the reply. "Where did you find that?"
"On the river bank, where the canoe the men came in was beached," was the reply.
"Well," observed the Captain, "if we can't learn why they went away, or how, we may at least be able to discover where they went. Let us be about it."
"Unfortunately," Ned replied, "we can't track them through the waters of the channel. Water shows no footprints!"
"But they might not have gone away by water," insisted the other. "If they had, they would have taken the motor boat."
"They did send a man to get it," Ned replied, "but he couldn't operate it. That is why it was out of order this morning."
"How do you know that?"
"The man used matches there—the same kind of matches used in that room."