Murder in the Void

The black, moonless Venus night lay solid over the big metal house and its surrounding grounds. The young Earthman who was creeping stealthily through clumps of weird shrubbery and enormous flowers toward the house thanked heaven fervently for the cloudy planet's stygian nights.
But Rab Crane knew that it was deadly dangerous approaching the house of Doctor Alph, even under cover of darkness. For the Venusian scientist's home had become a focus of interplanetary intrigue in the last few weeks. Every splanet in the System had heard the rumor of Doctor Alph's discovery of a tremendous new scientific weapon. And every one of them had agents trying to secure it. There would be guards inside the house, without doubt.
Crane's bronzed, aquiline face tensed as he crouched for a moment beside a stiff, grotesque shrub. As a member of the Terrestrial Secret Service he had been sent by the TSS to get Doctor Alph's secret weapon and he'd do it or die trying.
Not a light showed from anywhere in the dark, square metal house.
Too quiet, muttered Crane to himself. Looks like a trap.
He shifted his stubby beam-pistol to his left hand, and with his right drew a compact little instrument from his pocket. Then he moved silently on toward the dark house.
Here goes nothing, he whispered. In two minutes I'll probably rate a nice memorial plaque at headquarters.
Like a sliding shadow, Crane flattened against the side of the house, just beneath a window. He reached up with the little oval instrument he held.
It was a recorder which registered the presence anywhere nearby of invisible watchmen, those diabolically ingenious combinations of electric eyes and atomic beams, effective alarms that blasted down intruders without warning.
To Rab Crane's amazement, the recorder showed no such protective devices in operation around the window. What did it mean? It looked to him like a deliberate trap set by the Venusian scientist.
But he had to go through with it. Too late to back out now. He severed the catch of the window by a single tiny, smothered flash from his beamgun. He rolled the flexible glass quickly aside and drew himself rapidly up into the dark room. He poised motionless in the dark, listening. The house was as silent as the grave. He could not understand it but his instincts warned him of peril.