Sarah’s broken leg was still bothering her, but Gunter was a godsend, gladly bringing her fresh cups of decaf while she sat at the desk in the room that used to be Carl’s.

She was still working with the stack of papers Don had brought from the university — a hardcopy of the reply that had been sent to Sigma Draconis from Arecibo, and the source material it was based on: the one thousand sets of survey answers that had been chosen at random from those collected on the website. The decryption key must be somewhere buried in there, Sarah felt sure.

It had been decades since Sarah had looked at these documents and she only vaguely remembered them. But Gunter had merely to glance at each page to be able to index it, and so when Sarah said, for instance, "I remember a pair of answers that struck me as contradictory — somebody who said ‘yes’ to the question about terminating no-longer-productive old people, and ‘yes’ to the question about not terminating people who were an economic burden," the robot had replied, "That’s in survey number 785."

Still, she found herself often angry and sometimes even crying in frustration. She couldn’t think as clearly as she used to. Perhaps that wasn’t obvious in her day-to-day life of cooking and dealing with grandkids, but it was painfully clear when she tried to puzzle things out, tried to do math in her head, tried to concentrate, to think. And she grew fatigued so easily; she found herself often needing to lie down, which just prolonged the work even more.

Of course, many people had already gone back to look at the message sent from Arecibo to see if it contained the decryption key. And, she realized, if those keen young minds hadn’t found it, she likely didn’t have a prayer.

Many had suggested that the key might be one particular set of answers, from one of the thousand surveys: a unique sequence of eighty-four responses, one for each question, something like "yes," "no," "much greater than," "I prefer option three," "equal to," "no," "yes," "less than," and so on. There were over 20,000,000,000,000,000,000,000,000,000,000,000,000,000 possible combinations, Sarah knew. Those who didn’t have access to the full Arecibo transmission might be trying sequences at random, but even with the world’s fastest computers it would take decades to test them all. Others, of course, did have the full reply that had been sent, and had doubtless already tried using each of the thousand answer strings in turn, but had failed to unlock the message. Sarah continued to pour over the original surveys, looking for something — anything — that might stand out. But, damn it all, nothing did. She hated being old, hated what it was doing to her mind. Old professors never die, the joke went. They just lose their faculties. It was so funny, as her friends at public school used to say, that she forgot to laugh.

She tried another sequence, but again the message "Decryption failed" flashed on her monitor. She didn’t slam her hand down on the desktop in anger — she didn’t have the strength for that — but Gunter must have read something in her body language anyway. "You seem frustrated," he said.

She swiveled her chair and looked at the Mozo, and a thought occurred to her.

Gunter was an example of a nonhuman intelligence; maybe he’d have a better idea of what the aliens were looking for. "If it were you, Gunter, what would you have chosen as a decryption key?"

"I am not disposed to secrecy," he said.

"No, I suppose not."

"Have you asked Don?" the Mozo said, his tone even.

She felt her eyebrows going up as she looked at the robot. "Why do you say that?"

Gunter’s mouth line twitched, as if he’d started to say something then thought better of it. After a moment, though, he looked away and said, "No special reason."

Sarah thought about letting it go, but…

But, damn it all, Don had his confidant. "You don’t think I know, do you?"

"Know what?" asked Gunter.

"Puh-lease," she said. "I can translate messages from the stars. I can certainly pick up signals closer to home."

You could never tell if a robot was meeting your gaze. "Ah," said Gunter.

"Do you know who it is?" she asked.

The Mozo shook his blue head, then: "Do you?"

"No. And I don’t want to."

"If I may be so bold, how do you feel about this?"

Sarah looked out the window — which showed some sky and the red bricks of the house next door. "It would not have been my first choice, but…"

The Mozo was silent, infinitely patient. At last, Sarah went on. "I know he has…"

She vacillated between saying "wants" and "needs," and finally settled on the latter.

"And I can’t become a — a gymnast. I can’t turn back the clock." She realized she’d said the part about the clock as if citing an archetypal impossibility like "I can’t make the sun stand still." But for Don, the hands — good God, when had she last seen a clock with hands? — had indeed been turned way, way back. She shook her head. "I can’t keep up with him, not anymore." She was quiet for a time, then looked at the robot. "How do you feel about this?"

"Emotions are not my forte."

"I suppose."

"Still, I prefer things to be… simple."

Sarah nodded. "Another admirable trait you have."

"As we have been speaking, I have been accessing the web for information on such things. I freely confess to not understanding it all, but… are you not angry?"

"Oh, yes. But not, so much, at Don."

"I do not understand."

"I’m angry at — at the circumstances."

"You mean that the rollback did not work for you?"

Sarah looked away again. After a moment, she spoke, softly but clearly. "I wasn’t angry that it didn’t work for me," she said. "I was angry that it did work for Don."

She turned back to face the Mozo. "Awful, isn’t it, that I should be upset that the person I love most in all the world is going to get another seventy years or more of life?" She shook her head, amazed at what she’d found herself capable of. "But, you know, it was because I knew what was bound to happen. I knew he would leave me."

Gunter tilted his spherical head. "But he hasn’t."

"No. And, well, I don’t think he’s going to."

The robot considered this, then: "I concur."

Sarah lifted her shoulders slightly. "And that’s why I have to forgive him," she said, her voice soft and faraway. "Because, you see, I know, in my heart of hearts, if the situation had been reversed, I would have left him."

"How do you feel?" asked Petra Jones, the Rejuvenex doctor, who had come by the house for Don’s latest checkup. Sarah never sat in on these anymore; it was too much for her to bear.

Don knew he suffered from a misplaced stubborn pride. When his mother had been dying, slowly, painfully, all those years ago, he’d toughed it out. When Sarah was fighting her battle with cancer, he’d kept his chin up, hiding his pain and fear as best he could from her and his children. He was his father’s son, he knew; to ask for help was to show weakness. But he needed help now.

"I- I don’t know," he said softly.

He was sitting on one end of the couch; Petra, clad in an expensive-looking burnt-orange pantsuit, was at the other. "Is something wrong?" she asked, leaning forward, the beads in her dreadlocks making soft clicking sounds.

Don tilted his head. He could just make out Sarah and Gunter talking, upstairs in the study. "I, um, I haven’t really been feeling like myself," he said.

"In what way?" Petra said, the words lilting a bit thanks to her slight Georgia accent.

He took a deep breath. "I’ve been doing… uncharacteristic things — things I never thought I would do."

"Like what?"

He looked away. "I, um…"