"The box!" cried Billie. "Quick, Lucia, look and see if the box is gone!"
The girl rushed back into the library and she, too, gave a shriek.
"It's gone!" she cried. "It's gone!"
The boys sprang up the stairs three at a time and into the library. Lucia was right. The box was gone.
"It must be the old boy, sure enough," said Billie, "or at least one of his imps." Then to the maid: "How did he get in?"
"I don't know, señor. I only saw him go out. He went right through the door without opening it."
"Nonsense!" from Donald. "His Satanic majesty might go through a solid door, but the box wouldn't. There is some other explanation."
"But who could it be?" queried Lucia in great fear.
"Some one who knows the house," declared Adrian emphatically. "He may have put on some masquerade costume just to frighten these superstitious servants in case he was discovered."
"I believe Ad is right," agreed Donald. "What do you think, Billie?"