casually. âWe wondered how you can fly without license numbers.â
âThatâs none of your business!â the man snapped. âItâs due for a new paint job at the end of this run, since youâre so worried about it. Now Iâll thank you to move on.â
He turned to the gas-truck driver. âGet me a taxi,â he said.
The driver nodded, completed his refueling job, and rode off with the pilot. At the same moment Cap Bailey pulled up in an old-fashioned rented car, and the boys put the luggage on its roof. Then they set off for the fossil area. Twenty minutes later they reached the famous spot.
âThe sand really has a greenish look,â Frank observed.
Cap smiled. âYouâll find that the study of fossils is pretty interesting. Paleontologists who dig for them are the detectives of the past, and fossils are their clues. You can tell from them what the climate was and if the place where they lie buried was dry land or ocean. The land weâre standing on was once deep beneath the sea.â
âThis far inland?â Joe asked.
âEven farther. This green sand was left behind by an immense sea that covered the eastern part of the country many centuries after brachiopods became extinct. By the way, this sand is very good fertilizer.â
âLike cheese, eh? When itâs green, itâs ripe!â Joe quipped.
The conversation turned to more serious matters. Cap asked the boys if they felt sure they had eluded any pursuers interested in stealing his map of Wildcat Swamp.
âI donât trust that pilot who flew in right after we did,â Frank answered.
âSince we seem to be watched,â Joe said, âmaybe we ought to rig up a booby trap.â
âWhat kind?â Cap asked.
âWell, if I were after any papers of yours, Iâd figure they were in that brief case you carry. Letâs take out whatâs important and leave the case in the car. Then we can walk out into the dry lake, circle around, and watch.â
âAnd in case someone takes that brief case, how about a little of this powder?â Frank suggested as he opened one of the bags and took out a plastic vial.
âWhat is it?â Bailey asked.
âA special dye powder. Weâll sprinkle it lightly over your brief case. Itâs the same color as the leather, but if anyone gets it on his hands, a blue stain will show up in a few minutes. And heâll have a terrible time washing it off.â
âWe may not catch the villain red-handed, but weâll sure catch him blue-handed.â Joe chuckled.
The trap was laid quickly and the car parked in plain sight. The three worked their way across the dry lake bed, around boulders, and through scraggly stunted brush toward the top of a hill.
But before they could reach the summit, a voice hailed them, âHey there! What are you up to?â
Cap and the Hardys stopped in their tracks and turned. A uniformed policeman had dismounted from a horse and was hurrying toward them.
âIâve been watching you,â the officer puffed. âYou donât act like fossil hunters to me. I patrol this area every dayâlots of professor guys get lost out hereâbut youâre not fossil men. You donât even have any equipment.â
Cap told the policeman of the trap they had just laid and why. âWill you help us?â the teacher asked.
The policeman became interested. âHm! Sounds exciting, and nothing exciting ever happens out here. My inspectionâs over. Iâll go along with you.â
He plodded behind the others up the low hill and crouched with them in a clump of thick brush.
Joe whispered excitedly after a few minutes, âLook!â
There was a movement in the weeds near the car. Suddenly two men stood upright and glanced about furtively. Then, swiftly and silently, they moved to the car and opened a rear door.
CHAPTER V
Into Perilous