that a fact, Frank? Did somebody break into your place last night?
I remember now that I did see you pottering about your craft up there
somewhere about the Quackenboss place, but I'd forgotten it till the
Chief mentioned that you didn't have it in the hangar. That's the time
you were lucky. See what I got for having mine at home all snug and
nice. It's been hooked clear as anything, and not a trace to tell who
did the business."

"Hold on there, Percy," said the Chief, with a broad smile, "perhaps it
isn't such a deep mystery after all."

"Tell me what you mean when you say that," demanded the boy, loftily, as
though he resented the fact that anything should be kept from him a
single second.

"Why, Frank and Andy found these things in their shop, left by the two
men who tried to get their hydroplane; and the chances are ten to one
the same parties went right straight over to your place and got yours as
a second choice."

"I don't like the way you speak of my biplane, Chief, which cost ever so
much more money than the contraption the Bird boys own," Percy remarked,
sneeringly; "but never mind, tell me what these things stand for. An
electric torch and--why those things look like black masks. Great
Caesar! and the Bloomsbury bank was robbed last night, they told me when
I was rushing around looking for you. See here, do you think the yeggs
who did that neat job got away with my biplane?"

Percy was getting more excited than ever now. When he did, he seemed to
just foam a little at the corners of his mouth, his eyes glittered, and
his face turned red.

"There seems to be no doubt of it," replied the Chief, calmly, and yet
with a stiffening of his figure, as though conscious of having already
discovered a most promising clue, that could not but reflect credit on
his astuteness as an officer of the law.

"They knew all about Frank's machine and mine too, then?" continued
Percy, still grappling with the tremendous problem.

"Looks that way," the official went on to remark, "and makes me think
more than ever that they must have a friend right here in Bloomsbury who
put them wise to lots of things. Time'll tell that. But I don't suppose
you found anything around your place like Frank did, to tell that some
strangers had been there while you slept?"

"Not a blessed thing; though, to tell the honest truth, I didn't hang
around long when I found my biplane was gone. It was the best machine I
ever owned, and as you know