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.
Soundlessly he moved across the dark room. He knew that Doctor Alph's laboratory lay at the back of the house. There, if anywhere, he might find some clue to the Venusian scientist's great discovery that had so perturbed the planetary governments.
He watched his little recorder alertly as he advanced, expecting it each moment to flash the tiny signal spark that would warn of a network of deadly beams ahead. But it gave no signal. Apparently the whole web of the houses protective beams had been turned off at the main switch. But why?
* * *
Crane moved quickly out of the room into an equally dark hall. In the hall he tripped on something soft and recoiled, his gun-arm stiffening.
He heard no sound. In a moment he ventured to flash a tiny needle of light from a ring on his finger, onto the floor. His breath sucked inward with a sharp hiss. A Venusian house-guard lay there! One glance assured him the man was dead.
The man's neck had been broken cleanly, as though by a twist of powerful hands. The marks of the killer's hands were still visible, red against the Venusian's milky white skin. A beam-gun was still in his limp hand.