He stopped abruptly, his hands gripping the half-open doors.
"The deuce!" he ejaculated.
CHAPTER VI
THE INTERRUPTED VIGIL
"What's wrong?" enquired both lads anxiously, for the worried expression on the usually calm features of the inventor told its own tale.
In his agitation Blake failed to make reply. He dashed into the shed, followed by his two assistants. Everywhere there were signs of disorder as if some intruder had hastily overhauled the secrets of the jealously guarded spot. The high tension wire that had previously baulked a nefarious attempt had been severed by means of a pair of insulated wire-cutters. The lens of the tell-tale camera had been smashed and the dark slide removed and exposed to the light.
A safe, cunningly built into a concrete pier of the shed, had been forced open and its contents removed.
"The spy has secured the plans; that's pretty evident," he declared. "We can do no good here at present. What I want to find out is how the fellow forced his way into the grounds."
Accompanied by Athol and Dick, the inventor left the shed and hurried across the snow-covered ground. Already the footprints of the intruder had been obliterated by the falling flakes. He could not have chosen a better time for his successful attempt.