s snapped on. Curlie's fingers flew from instrument to
instrument. The voice of the mysterious operator could be heard. Now
rising, now falling, it filled the woods with echoes, yet the speaker
was more than a mile away, as near as the boys could guess.

The words spoken by him were now of no importance. Location was
everything.

"Same place," exclaimed Curlie, "exactly the same! You know where! Drive
like mad!"

Instantly the car lurched forward. Coming out of the bush on two wheels,
she sent a shower of gravel flying as she rushed madly down the road.

Quick as they were, the quarry had been quicker. As they rounded a
corner, they caught the red gleam of a tail-light disappearing at the
next turn.

"Heck!" said Curlie, then, "Let her out! Show him some speed."

The motor of the Humming Bird sang joyously. Fairly eating up the road,
she took the corner with a wide swing. But when they looked down the
long stretch of highway there was no red tail-light to be seen.

"Heck!" said Curlie again, "he's reached the next crossroad and turned
the corner. Can't tell which way he went. It's a hard, dry gravel
roadbed--won't tell a thing. Best we can do is to rattle along up there,
then sit it out for another listen-in."

Disappointed but not disheartened, Curlie adjusted his instruments, then
sat in breathless expectation.

He did not have long to wait, for again the voice in the loud speaker
boomed out into the night.

"Huh," he grumbled a few seconds later, "he's got three miles lead on
us. To the right. Quick, give her the gas."

Again they were off. For two miles and a half straight ahead they raced.
The Humming Bird quivered like a leaf, instruments jingling in spite of
their lashings.

"Make it all the way," said Curlie, as Joe slowed up. "He's not there.
Given us the slip again."

Six times this program was gone through with. Not once in all that time
did they catch sight of that tail-light.

"Some car he's got!" said Curlie when the farce was ended. "Bet he
never even guessed he was being chased. But you wait; we'll get him
yet."

When they were once more in the secret tower room Curlie plotted the
route of the mysterious operator.

"Only significant thing about that," he commented, when he had finished,
"is that he starts and finishes within a quarter of a mile of the same
place as on the other two nights."

"And that place--" suggested Joe.

"Is near old J. Anson's driveway."

"Looks mighty sus