Even though it was still night, the rugged landscape was not truly dark. Earthglow bathed the rolling, pockmarked ground. Paul could see the rocks strewn across the bare regolith, the rims of craters deep enough to swallow him, the dents of smaller ones that could make him stumble and fall if he wasn’t careful.

Nothing but rocks and craters, and the sharp uncompromising slash of the horizon out there, like the edge of the world, the beginning of infinity. Not a blade of grass or a drop of water. Harsh, bare rock stretching as far as the eye could see in every direction.

Yet Paul had always loved it. Even encased in a bulky, cumbersome surface suit he had always felt free up here on the surface of the Moon, on his own, alone in a universe where he had no problems at all except survival. That’s what the Moon gives us, he told himself. Brings it all down to the real question, the only question. Are you going to live or die? Everything else is bullshit. Am I going to live or die?

But then he thought of Joanna again, and he knew that there was more to it. Would she live or die? Was Greg crazy enough to kill her, too? It’s more than just me, Paul realized. Even here, a quarter-million miles from Earth and its complications, he was not alone. Even though there was not another living human being — not another living thing of any kind — this side of the mountains that marked the Alphonsus ringwall, Paul knew that other lives depended on him.

Joanna. Mustn’t let Greg get to Joanna. Got to stop him.

He stopped, puffing hard. The visor of his helmet was fogging. A flash of panic surged through him. Have the nanobugs gotten to this suit? He held up his left arm to check the display panel on the suit’s forearm, trembling so badly that he had to grasp his wrist with his right hand to steady himself enough to read the display. Everything in the green. He tapped the control for the air-circulating fan in his helmet and heard the comforting whine of its speeding up.