He heard them rummaging above, attempting again and again to pull open the hatch. It had happened this way for years: They'd try to open the trapdoor for an hour or two, then give it up and turn their attention to something else. They never thought to turn the handle. Maybe an undeep person wouldn't be able to reason the combination clicks, but only a completely flat one would persist in pulling when it always ended in failure.
Possibly, he thought, the cosmic rays had been more destructive to their egg cells. Or maybe the alien radiations subtracted something from the other cells to add to his. If this were true, he was partly a product of the others and owed his depth to them.
Adam felt sorry for his cousins then and wished he hadn't hurt them by avoiding their presence. Despite their undepth, they must have feelings. The mecs probably wouldn't have been able to give them depth but, he remembered, the other role of the mecs was to prevent each one of them from harming the others. In their role as arbitrator, Adam realized, they might have stopped him from hurting them so.
Filled with remorse, he left his desk-chair and walked stoop-shouldered under the low ceiling. At the trapdoor, he opened the combination on the inside lock handle and pushed upward. It wouldn't open. He tried again, but it wasn't the lock that was stuck. They must have slid something heavy over the hatch, something he couldn't move.
He tried calling to them, but his voice was lost in the insulative metal of the deck. Finally he sat down, conserving his strength for a final onslaught.
If he couldn't open the hatch, he realized vividly it would be not only his failure, but the failure of the human race.
But maybe it did not have to be so. Maybe the differences in the others weren't biological—maybe they were environmental. And with that thought, he made his way through the narrow passageway and reversed his deed of eleven years past. He turned the mecs back on.
Returning to the hatch, he reworked the combination to make sure it was not the lock that held him. He pushed upward with all his strength, steadily with increasing pressure, until the beads of perspiration turned into gulleys that streamed down his face.