“I didn’t mean to be curious,” she faltered. “I’m sorry!” Even her words sounded empty of meaning.

Another change came over the face of Dimitri Uzlov.

“You will be so good as to pardon me for my seeming ill haste,” he murmured. “But that picture—no—it must not be seen—yet.”

Matters were becoming a little strained and awkward, but Terry went into the breach cleverly by saying:

“We had better be going. It must be nearly lunch time. Mother will be expecting us. Thank you for your help, Mr. Uzlov, and for letting us see your houseboat.”

He did not try to stop them, nor did he express regret at their sudden departure, but simply said good-bye and then watched them pull away in the waiting rowboat.

“Queerest person I ever met,” Terry began. “One minute all sunshine and gladness, and the next, all worked up because Arden asked about his old picture.”

“I wouldn’t have touched it, anyway,” Arden replied. “I was just trying to show a little interest. My goodness! Who would want to live in such a messy place? No one but the sort they call—artists!”

“I wonder what the hidden picture was?” Sim asked curiously. “Perhaps he’s a spy, making maps of the coast and inlet.”

“Now who said they refused to get mixed up in another mystery?” Terry jeered. “Well, let’s go home, I’m hungry.”