unless—" Verana's eyes widened until the pupils were surrounded by circles of white—"unless we were in outer space!"

We stared at the metal door that had imprisoned us, afraid even to speak of our fantastic suspicion.

I deactivated my radio.

Marie screamed as an inner door opened to disclose a long, narrow corridor beyond.

Simultaneous with the opening of the second door, I felt air press against my spacesuit. Before, our suits had been puffed outward by the pressure of air inside. Now our spacesuits were slack and dangling on our bodies.

We looked at each other and then at the inviting corridor beyond the open door.

We went single file, first Kane, then his wife Marie. Verana followed next and I was the last.

We walked slowly, examining the strange construction. The walls were featureless but still seemed alien. At various places on the walls were the outlines of doors without handles or locks.

Kane pressed his shoulder against a door and shoved. The door was unyielding.

I manipulated the air-vent controls of my spacesuit, allowed a small amount of the corridor's air into my helmet and inhaled cautiously. It smelled all right. I waited and nothing happened. Gradually, I increased the intake, turned off the oxygenating machines and removed my helmet.

"Shut off your oxy," I suggested. "We might as well breathe the air in this place and save our supply. We may need the oxygen in our suits later."

They saw that I had removed my helmet and was still alive and one by one removed their own helmets.

At the end of the corridor, Kane stopped before a blank wall. The sweat on his face glistened dully; his chest rose and fell rapidly. Kane was a pilot and one of the prerequisites for the job of guiding tons of metal between Earth and the Moon was a good set of nerves. Kane excited easily, his temper was fiery, but his nerves were like steel.

"The end of the line," he grunted.

As though to disprove the statement, a door on his right side opened soundlessly.

He went through the doorway as if shoved violently by an invisible hand.

The door closed behind him.

Marie threw herself at the door and beat at the metal. "Harry!"

Verana rushed to her side. Another door on the opposite side of the corridor opened silently. The door was behind them; they didn't notice.

Before I could warn them, Marie floated across the corridor, through the doorway.

Verana and I stared at the darkness beyond the opening, our muscles frozen by shock.

The door closed behind Marie's screaming, struggling form.

Verana's face was white with fear. Apprehensively, she glanced at the other doors that lined the hall.

I put my arms around her, held her close.

"Antigravity machines, force rays," I suggested worriedly.

For several minutes, we remained motionless and silent. I recalled the preceding events of the day, searched for a sense of normality in them. The Kanes, Miller, Verana and I lived in Lunar City with hundreds of other people. Mankind had inhabited the Moon for over a year. Means of recreation were scarce. Many people explored the place to amuse themselves. After supper, we had decided to take a walk. As simple as that: a walk on the Moon.

We had expected only the familiar craters, chasms and weird rock formations. A twist of fate and here we were: imprisoned in an alien ship.

My legs quivered with fatigue, my heart throbbed heavily, Verana's perfume dizzied me. No, it wasn't a dream. Despite our incredible situation, there was no sensation of unreality.

I took Verana's hand and led her down the long corridor, retracing our steps.

We had walked not more than two yards when the rest of the doors opened soundlessly.

Verana's hand flew to her mouth to stifle a gasp.

Six doors were now open. The only two that remained closed were the ones that the Kanes had unwillingly entered.

This time, no invisible hand