THE INVISIBLE FOOTPRINT
“I scream?” The girl in the patched knickers sitting before the roaring
fire stared at Red Rodgers. “Why should I scream?”
“I don’t know.” Red was puzzled. “I only know I heard you.”
“But I did not scream.”
It was Red’s turn to start. He had heard a scream. No man, even in mortal
agony, could scream in that manner. What did it mean? Who—?
His thoughts were broken off by a sudden burst of laughter. It was the
mystery girl.
“That—that,” she stammered, with an effort at self control. “It was not I
who screamed, but a loon, a silly old loon! Have you never heard a loon
scream in the night?”
“Never.”
“Then you are to be forgiven. When a loon goes about the business of
screaming in earnest, he can put a drowning woman to shame. We who have
heard them often become so accustomed to them that we scarcely hear them
at all.”
Red stared first at the girl, then at the fire. He was wondering in a
vague sort of way just how much he had missed by living all his life
within the confines of a city. He was to wonder this many times before
this business of being kidnaped and carried to a deserted island was
over.
“I wonder what that old loon is doing here?” the girl mused. “All his
pals must have gone south by now. The gulls stay all winter. Some kinds
of ducks, too, and the jays and the chickadees. It can’t be very lonely
here even in winter. Wouldn’t it be thrilling if we had to stay here on
and on?”
Red stared harder at the fire as he tried in vain to think what that
would be like.
“You seem to know a lot about this island,” he blurted out quite
suddenly. “How does it happen that kidnapers bring you to a place where
you have been before? Seems a trifle mixed.”
“I’ve wondered about that.” Her big blue eyes were round and frank. “I
think I’ve got it figured out. Do you believe in God?”
“Why, yes, I—I do. I’ve prayed about football sometimes; asked the One
who gave me my body to help me keep it clean and fit; asked Him, too, to
give me a clear brain and a sharp eye for every play.”
“Oh,” she breathed, dropping a hand gently on his arm, “I’m glad! Because
I—I believe in God. I hope He outwits evil men. And I—I’ve sort of felt
that He saw that those men were going to carry us off, you and me, so He
sort of winked, don’t you know, like the man in the moon seems to do, and
He said: ‘I’ll have those kidnapers take that boy and girl to the island
where the girl has spent her summers as long as she can remember.’ And
so, don’t you see? Here we are.”
“That,” said Red with conviction, “that’s great!”
Reaching for a large spruce log, he threw it on the fire. When the shower
of sparks had subsided, he turned to her eagerly.
“What place is this? Tell me about it, all you can. We—we may be parted
at any moment. And I—I need to know a lot. In the end they may get us, at
least one of us, and the other must be able to make his way out, in the
end, to see that justice is done.”
At the thought of the kidnapers he strode to the door and opened it a
crack.
“Safe enough for the present.” His tension relaxed. “It’s snowing,
snowing hard. They’ll never find us here in a snowstorm.”
“You are right,” she replied quietly. Her eyes closed. They remained
closed so long that Red thought her asleep. But again they opened. “You
are right, they will not find us in the snow. You should know about this
place. I will tell you all I can. And then—then we must rest, for long,
hard hours are before us. It is difficult, perhaps impossible, to escape
from this place in November. But we must try.”
“What place is this?” the boy asked once more.
“What? You don’t know our island?” The girl’s eyes opened wide. “This,”
her tone became impressive, “this is Isle Royale!”
“She expects me to be greatly surprised,” Red said to himself. Out of
respect for her desire he did his best to show great astonishment. The
truth was that the part of social science that deals with the world we
live in had interested him very little. He was all for chemistry,
physics, mathematics. He had no more notion where Isle Royale was than
the Little Diomede Island, or King William’s Land. He had never heard of
it. “But she evidently thinks it a great place,” he told himself, “so
great it shall be.”
“Tell me more about it,” he demanded at last. He was truly interested. If
he was to escape from this island, wild and uninhabited as it appeared to
be, he must at least know his way about.
* * * * * * * *
In the meantime, Tom Howe, in his box-like laboratory, had revealed to
Johnny Thompson’s astonished eyes a bit of scientific crime detection
that for sheer cunning would have put any ancient astrologer or alchemist
to shame.
Having spread the bed sheet taken from Red Rodger’s berth out on a small
table, he had switched on a 200-watt lamp and had proceeded to examine it
inch by inch as he slid it across the table.
“Not a mark,” Johnny commented, as the examination was completed.
“I’m not so sure,” Howe drawled. “A man stepped on that sheet, a very
heavy man. He left a deep dent in the mattress and bedding. It’s hard to
step on anything as clean as a sheet without leaving some sort of mark.
“Let’s see.” He drew the sheet endwise until the very center rested on
the smooth top of the table. “It would be about there.”
He turned off the powerful light. At once the room was plunged in utter
darkness.
Then, while Johnny waited as breathless as a child at his first picture
show, a curious violet light pervaded the room.
“Look!” Tom Howe whispered, pointing to the center of the sheet.
Johnny did look, and there, to his vast astonishment, he beheld quite
clearly outlined the footprint of a man.
“The sole of a heavy shoe!” He was dumbfounded. “It was not there before!
And see! There are the marks of the nails; a heavy workman’s shoe. You
could count those nails. And a heel of some hard, prepared stuff with the
maker’s name wrong way over.”
“Yes,” Howe added quietly, “and a deep, jagged cut across the sole.
Slipped on some sharp stone perhaps, when the sole was wet. That marks
the shoe. It’s not like any other shoe in the world. Find that shoe, find
the man who wears it, and we have made a discovery of great importance.”
“But I don’t understand!” Johnny was puzzled. “That mark was not there a
moment ago.”
“Nor is it now.” Tom Howe chuckled. The violet light faded; the brilliant
white light flashed on. The footprint was gone.
“Magic!” Johnny murmured. “Some form of magic. You can’t convict a man
with magic.”
“Not magic, but science!” Howe’s tone was impressive. “Crooks are
learning to use science as an aid in committing crimes. We must use
science to detect crimes.”
Once again the white light was gone; the violet light returned and with
it that mysterious vanishing footprint.
“You see,” Howe explained, “when that fellow entered the car to assist in
carrying the famous football star away, he had been walking over a
surface that contained some chemical solution. If he had passed over damp
coffee grounds, or through a forest where rank vegetable matter rotted,
the effect would have been as you see it now. His foot would have left a
mark invisible in white light, but quite clearly outlined when subjected
to the rays of an ultra-violet lamp.
“This lamp,” he went on, “has detected the secret writing of many a spy
and jailbird. A spy, wishing to forward a secret report, dips his pen
into a liquid made by soaking a few quinine pills in water. This writing
will not show in white light until it has been treated. He writes some
commonplace letter over this message and sends it forth. Our Secret
service men seize it, put it under the ultra-violet lamp, and there it
is; you can read every word. The moment the lamp is snapped off the
message is gone.
“A criminal may dip the corner of his jacket in coffee, return to his
cell, wring out the coffee and write with the coffee a secret message to
some one who plots his deliverance. He, too, may be caught by this
ultra-violet lamp.
“So now,” he concluded, “we have only to find the man who wears this
shoe. Very simple in a city of three million.” He smiled a slow smile.
“All the same, it’s a step.”
“An invisible step,” Johnny chuckled.