s handicapped them
immensely, so that the two defenders kept a cleared circle about them.

One of the attackers, more daring than the rest, leaped forward to
engage the engineer. He collapsed with a crushed skull.

Then, when victory seemed in their grasp, luck turned. At Jack's next
blow the stock of his weapon parted from the barrel, leaving him
almost defenseless. At the same time Manthis slipped and collapsed
from a knife thrust.

* * * * *

Jack was left alone to face three enemies and would have been killed
within the minute had not Solinski, recalling the little time he had
left to stop the interfering wave, deserted his comrades and sprinted
for the laboratory.

The seeming defection of their chief threw the other two attackers
into momentary confusion. Before they could recover, Jack knocked one
out with the gun barrel, then came a flying tackle at the other.

But he had caught a tartar. His remaining enemy was a gigantic Negro.
Recovering from his surprise the latter lifted high a glittering knife
to finish his disarmed foe. Jack snatched at the uplifted arm--missed!

A revolver cracked. The hooded Negro staggered, then crashed forward.

"Remembered my pistol just in time," gasped the doctor from the floor.
"Don't bother about me. I'm all right. Stop Solinski, for God's sake."

Although his lungs seemed bursting Baron turned and flew up the
stairs. Being familiar with every turn, he gained on the Russian and
caught sight of the dreadful black coat-tails as his enemy burst
through to the twentieth floor. The locked door of the apartment
baffled him only a moment. Stepping back, Solinski hurled his giant
frame against the panels. They splintered and crashed inward. But the
delay allowed Jack to catch up.

He leaped on the Russian's back. Locked together they reeled into the
living room. For a fleeting moment Jack saw June sitting rigidly at
the instruments. Her eyes were starting from their sockets but her
hands were steady.

"I warned you to kill yourself," Solinski's voice rose in a screaming
whisper through the respirator. "Now I will do it." Displaying the
strength of madness he hurled Jack from him. Losing all control of his
limbs, the younger man flew across the room and demolished the divan
in his fall. But the thought of what Solinski would do to June
brought him back to the attack.

* * * * *

The fury of their struggle wrecke