caution at his aide. "We'll explain matters to him."

Wondering what could be the mission of the two officers, Mrs. Baggert
led them to the library.

"It's queer," she thought, "that they don't ask something about the
airship. I suppose that was what they came for. But maybe it's about
the mysterious men who robbed Mr. Swift."

"Ah, gentlemen, what can I do for you?" asked the inventor, as he rose
to greet the officials.

"Ahem, Mr. Swift. Ahem-er-that is-well, the fact is, Mr. Swift,"
stammered the chief, "we have come upon a very painful errand."

"What's that?" cried Tom's father. "I haven't been robbed again, have
I?'

"There has been a robbery committed," spoke the constable quickly.

"But you are not the victim," interposed the chief.

"I'm glad of that," said Mr. Swift.

"Where is your son, Tom?" asked the head of the Shopton police force,
sharply.

"What do you want with him?" inquired the inventor, struck by some
strange tone in the other's voice.