Another room. A strip of light divided it into two dark halves. It speared down from a recessed groove in the ceiling, bisecting the wine draperies and the carpet, laying a bright band across the conference table. Tiny bright hyphens reflected from perspex workpads set into the mahogany.

A line in the sand. Patricia Rowan stood well back on the other side, her face half-lit in profile.

"Nice room," Scanlon remarked. "Does this mean I'm out of quarantine?"

Rowan didn't face him. "I'm afraid I'll have to ask you to stay on your side of the light. For your own safety."

"Not yours?"

Rowan gestured at the light without looking. "Microwave. UV too, I think. You'd fry if you crossed it."

"Ah. Well, maybe you've been right all along." Scanlon pulled a chair out from the conference table and sat down. "I developed a real symptom the other day. My stools seem a bit off. Intestinal flora not working properly, I guess."

"I'm sorry to hear it."

"I thought you'd be pleased. It's the closest thing to vindication you've got to date."

Neither person spoke for nearly a minute.

"I... I wanted to talk," Rowan said at last.

"So did I. A couple of weeks ago." And then, when she didn't respond: "Why now?"

"You're a therapist, aren't you?"

"Neurocognitist. And we haven't talked, as you put it, for decades. We prescribe."

She lowered her face.

"You see, I have," she began.

"Blood on my hands," she said a moment later.

I bet I know whose, too. "Then you really don't want me. You want a priest."

"They don't talk either. At least, they don't say much."

The curtain of light hummed softly, like a bug zapper.

"Pyranosal RNA," Scanlon said after a moment. "Five-sided ribose ring. A precursor to modern nucleic acids, pretty widespread about three and a half billion years ago. The library says it would've made a perfectly acceptable genetic template on its own; faster replication than DNA, fewer replication errors. Never caught on, though."

Rowan said nothing. She may have nodded, but it was hard to tell.

"So much for your story about an agricultural hazard. So are you finally going to tell me what's going on, or are you still into role-playing games?"

Rowan shook herself, as though coming back from somewhere. For the first time, she looked directly at Scanlon. The sterilight reflected off her forehead, buried her eyes in black pools of shadow. Her contacts shimmered like back-lit platinum.

She didn't seem to notice his condition.

"I didn't lie to you, Dr. Scanlon. Fundamentally, you could call this an agricultural problem. We're dealing with sort of a— a soil bacterium. It’s not a pathogen at all, really. It’s just— a competitor. And no, it never caught on. But as it turns out, it never really died off, either."

She dropped into a chair.