The door slammed shut.
Mark started forward. But the professor caught his arm.
"It is useless," the savant said. "To follow him would bring death and would avail nothing, my boy. He has won."
Like men in a daze, then, they stared into each other's eyes. They saw only dull hopelessness. The last spark was gone out.
Slowly, Mark walked over to the corner where stood the shattered mirror. Looked blankly down at its fragments. Bending, he picked up a splinter. Inspected it idly.
The next instant he whirled about.
"Professor Duchard!" he rapped. "How did this devil's looking-glass work?"
The scientist looked up dispiritedly, shrugged.
"I could not make you understand. It is a complicated matter of space-time theory—"
The other strode back to him. Gripped his shoulder.