And, to the surprise of them all, it did. As though it had been made for that lock, the little switch key slipped in. There was a click, a grinding sound, as the cover slipped on the sand-encrusted hinges, and the lid went back.
"Stung!" cried Roy, as nothing was seen but a slip of paper within the black interior.
Mr. Nelson lifted it out.
"I can't make anything of this," he said. "It's some sort of a note, written in cipher, I should judge. It is signed 'B. B. B.'"
"The same letters that are on top of the box," said Allen.
"Was there ever a pirate who had those initials?" asked Mollie, and the others laughed. "Well, there might have been," she went on. "I don't think it's so funny."
"Of course it isn't, dear," declared Betty. "I guess we're all a bit nervous. Is that all there is, Daddy?"
"Everything, my dear. The box is empty save for this bit of paper that doesn't make any sense."
"We must translate that at once, sir," said Allen. "If it is in cipher that's all the more evidence that it means something. I might have a try at that secret message, or whatever it is."
"Well, you're welcome to have a go at it," assented Mr. Nelson. "It may all be a joke, so don't take it too seriously."