The slow sound unsettled Iona and she slid the switch back up. However, the voice was higher and faster than Carter’s ought to be. Iona moved it down a little—and now found it too low. Her pulse suddenly rose, her hands trembling as she tried to locate the switch’s original setting, desperate to undo her meddling. The more she listened to the voice in subtle variations, the less she felt able to recall Carter’s true voice. Eventually she settled on something that sounded more or less right, but would other people notice if it was a little bit off? Would Carter notice if his voice was not quite his own?

The next diagram was headed PERSONALITY SETTINGS. Iona did not dare touch any of these but in case she did so accidentally, she fetched a pencil and on the back of the diagram she made a note of all the positions. There were perhaps fifty switches covering the personality functions. On the diagram they were labeled things like CHARM, STABILITY, MELANCHOLY, HUMOR, INTENSITY and each had a range of four settings. How much variation could be created with these simple controls? How many different personalities? The permutations were not infinite but the city could go through many, many generations before it had to start repeating the patterns.

The penultimate diagram had been annotated by hand. A series of switches at the bottom was marked with numbers 1 to 9 and then 0, and next to this was a long code. Iona guessed perhaps this was some security code to confirm her interference was authorized, and had to be input before closing the hatch? Whatever it was, it was part of the sequence and it seemed wise to carry it out.

The code contained over fifty digits and the switches were small and fiddly. When pressed, they made a click and then slid back into position of their own accord. Iona entered the code steadily, ticking off each number on the sheet as she went to ensure she made no mistakes. Finally she pressed a switch marked ENTER at the end of a row, and as instructed by the final diagram, closed the hatch.

Abruptly Carter stood and marched toward the door. Iona was startled and blurted, “Wait!” but he ignored her. No—it was as if he hadn’t heard her at all. He lifted the latch on her front door and walked outside.

Iona didn’t know what to do. Was Carter going to tell someone what had happened here? She had to make him listen—assure him she’d meant no harm by it. But right now he was walking away. She stepped outside, closed her door, and ran after him.

* * *

Iona caught up with Carter as he strode down the street away from her house. She fell into stride alongside him and spoke his name in a low voice but again, it was as if he had not heard.

“Where are you going?” said Iona.

Carter said nothing and kept walking.