"Exactly. Besides, just because we’re from the same planet doesn’t necessarily mean we should have more in common with them than with aliens. We actually have very little in common with dolphins. They don’t even have hands, but the aliens must."

"Whoa, Professor Halifax. How do you know that?"

"Because they built radio transmitters. They’ve proven they’re a technological species. In fact, they almost certainly live on dry land, again meaning we have more in common with them than with dolphins. You need to be able to harness fire to do metallurgy and all the other things required to make radio. Plus, of course, using radio means understanding mathematics, so they obviously have that in common with us, too."

"Not all of us are good at math," said the host, amiably. "But are you saying that, by necessity, whoever sent the message must have a lot in common with the sort of person who was trying to receive it?"

Sarah was quiet for a few seconds, thinking about this. "Well, I — um, yes. Yes, I guess that’s so."

Dr. Petra Jones was a tall, impeccably dressed black woman who looked to be about thirty — although, with employees of Rejuvenex, one could never be sure, Don supposed. She was strikingly beautiful, with high cheekbones and animated eyes, and hair that she wore in dreadlocks, a style he’d seen come in and out of fashion several times now. She had arrived for her weekly visit to check up on Don and Sarah, as part of a circuit she did visiting Rejuvenex clients in different cities.

Petra sat down in the living room of the house on Betty Ann Drive and crossed her long legs. Opposite her was a window, one of the two on either side of the fireplace.

Outside, the snow had melted; spring was coming. She looked at Sarah, then at Don, then back at Sarah again, and finally, she just said it. "Something has gone wrong."

"What do you mean?" said Don at once.

But Sarah simply nodded, and her voice was full of sadness. "I’m not regressing, am I?"

He felt his heart skip a beat.

Petra shook her head, and beads woven into her dreadlocks made small clacking sounds. "I am so sorry," she said, very softly.

"I knew it," said Sarah. "I- in my bones, I knew it."

"Why not?" Don demanded. "Why the hell not?"

Petra lifted her shoulders slightly. "That’s the big question. We’ve got a team working on this right now, and—"

"Can it be fixed?" he asked. Please, God, say that it can be fixed.

"We don’t know," said Petra. "We’ve never encountered anything like this before."

She paused, apparently gathering her thoughts. "We did succeed in lengthening your telomeres, Sarah, but for some reason the new endcap sequences are just being ignored when your chromosomes are being reproduced. Instead of continuing to transcribe all the way up to the end of your DNA, the replicator enzyme is stopping short, at where your chromosome arms used to end." She paused. "Several of the other biochemical changes we introduced are being rejected, too, and, again, we don’t know why."

Don was on his feet now. "This is bullshit," he said. "Your people said they knew what they were doing."

Petra flinched, but then seemed to find some strength. She had a slight accent to his ears; Georgia, maybe. "Look," she said, "I’m a doctor; I’m not in PR. We do know more about senescence and programmed cell death than anybody else. But we’ve done fewer than two hundred multidecade rejuvenation procedures on humans at this point." She spread her arms a bit. "This is still new territory."

Sarah was looking down at her hands — her swollen-jointed, liver-spotted, translucent-skinned hands, folded in her lap. "I’m going to stay old." It was a statement, not a question.

Petra closed her eyes. "I am so sorry, Sarah." But then she made her tone a bit brighter, although it sounded forced to Don. "But some of what we did was beneficial, and none of it seems to have been detrimental. Didn’t you tell me last time I was here that some of your day-to-day physical discomfort is gone?"

Sarah looked at Don, and she squinted, as if trying to make out someone far, far away. He walked over to her and stood next to where she was seated, placing a hand on her bony shoulder. "You must have some idea what caused this," he said sharply to Petra.

"As I said, we’re still working on that, but…"

"What? "he said.

"Well, it’s just that you had breast cancer, Mrs. Halifax…"

Sarah narrowed her eyes. "Yes. So? It was a long time ago."

"When we went over your medical history, prior to commencing our procedures, you told us how it was treated. Some chemotherapy. Radiation. Drugs. A mastectomy."

"Yes."

"Well, one of our people thinks that it might have something to do with that. Not with the successful treatment, which you told us about. But he wanted to know if there were any unsuccessful treatments you tried before that."

"Good grief," said Sarah. "I don’t remember all the details. It was over forty years ago, and I’ve tried to put the whole thing out of my mind."

"Of course," said Petra, gently. "Maybe we should speak to the doctors involved."

"Our GP from back then is long dead," Don said. "And the oncologist treating Sarah was in her sixties. She must be gone by now, too."

Petra nodded. "I don’t suppose your old doctors transferred records to your new doctor?"

"Christ, how should we know?" said Don. "When we changed doctors we filled out medical histories, and I’m sure we authorized the handing over of files, but…"

Petra nodded again. "But this was in the era of paper medical records, wasn’t it?

Who knows what’s become of them after all these years? Still, the researcher at our facility looking into this uncovered that about that time — early 2000s, right? — there were some interferon-based cancer treatments here in Canada that weren’t ever approved by the FDA in the States; that’s why we didn’t really know about them.

They’re long off the market; better drugs came along by 2010. But we’re trying to find a supply of them somewhere, so that we can run some tests. He thinks that if you had such a treatment, it might be what’s caused our process to fail, possibly because it permanently eliminated some crucial commensal viruses."

"Jesus, you should have screened more carefully," Don said. "We could sue you."

Petra rallied a bit and looked up at him defiantly. "Sue us for what? A medical procedure that you didn’t pay for that had no adverse effect?"

"Don, please," said Sarah. "I don’t want to sue anyone. I don’t…"

She trailed off, but he knew what she’d been about to say: "I don’t want to waste what little time I have left on a lawsuit." He stroked her shoulder reassuringly. "All right," he said. "All right. But can’t we try again? Maybe another round of treatments? Another attempt at rolling back?"

"We have been trying again," said Petra, "with tissue samples taken from your wife.

But nothing is working."

He felt bile climbing his throat. God damn — God damn everyone. Cody McGavin, for bringing this crazy idea into their lives. The people at Rejuvenex. The bloody aliens on Sigma Draconis II. They could all go to hell.

"This is ridiculous," said Don, shaking his head back and forth. He lifted his hand from Sarah’s shoulder, and then clasped both his hands behind his back and started pacing the length of the narrow living room, the room that had been home to him and his wife, the room his children had first learned to crawl in, the room that held so much history, so many memories — memories that he and Sarah had shared, decade after decade, good times and bad, thick and thin.

He took a deep breath, let it out. "I want you to stop the process for me, then," he said, his back briefly to the two women.