need."

The four friends went on into the store, where they found several of their
schoolmates, bent on the same mission as themselves. All exchanged
greetings, and many good-natured jokes were bandied back and forth as
they made their purchases.

"You fellows will have to step lively to get ahead of me," said Lon
Beardsley, who was older than any of the radio boys and was in the senior
class at High School. He was one of the brightest boys in his class, and
the others knew that competition from him was not to be despised.

"Stepping fast is one of the best things we do," said, Bob, in answer to
this friendly challenge. "You may be some speed, but we're not such
slouches, either."

"Do your worst! We defy you!" cried Herb, striking a melodramatic
attitude.

"All right," said Lon, laughing. "Remember, though, I've given you fair
warning. I see you're buying vacuum tubes," he added, curiously. "You must
be going in pretty deep, aren't you?"

"Ask us no questions and we'll tell you no lies," parried Bob. "Besides,
we're not the only radio fans in this town, Lon. Maybe some one else will
beat us all out."

"Oh, I'm not worrying," said the other, as he prepared to leave with his
purchases. "Are you fellows going my way?"

"You'd better not wait for us," replied Bob. "We've got a few things to
get yet. See you at school to-morrow."

"Righto!" said Lon, and departed, whistling cheerfully.

The radio boys started home soon afterward, The days were getting very
short, and by the time they left the store the autumn evening was rapidly
fading into night. There was a crisp tang in the air which, together with
the smell of burning leaves, gave warning that winter was close at hand.
The last gorgeous colors of an autumn sunset still tinged the western rim
of the sky as the boys set out for home at a rapid pace.

Not far from their homes they struck off from the street through a vacant
lot, following a path that served as a short cut. The lot was overgrown
with weeds and high sunflower stalks, but the idea of an ambush never
entered the boys' heads until suddenly they were assailed by a shower of
stones, which sang viciously past their ears. Fortunately, it was too dark
for their assailants to throw the missiles with any accuracy, although the
boys were struck more than once.

For a moment, taken completely by surprise, they did not know which way to
turn nor what to do. But they were not of the type that hesitates long