They talked about Rudy every day, how they would see that his memory was kept, how he would have been overjoyed at the poetry in the Sigma Hotel Book. How they missed him.

Hutch even began listening to country music, which she’d never done before. Years behind everybody else in her generation, she discovered Brad Wilkins, who always sang about moving on, and about the darkness outside the train windows.

When Antonio suggested they were becoming morose, that they should try to put the Sigma Hotel staircase behind them, Hutch agreed but really thought it was best to talk it out. Gradually, as the days passed, politics and black holes began to dominate the conversation. Rudy receded.

Three weeks and two days after leaving Sigma 2711, they arrived in the area that was home to Tenareif, roughly one and a half light-years from the position of the black hole.

They did a second jump, and, when they came out, Phyl announced immediately that she could see the target. “Take a look,” she said.

She put it on-screen: a luminous ring.

“That’s the accretion disk,” said Antonio. “It circles the black hole.”

“If not for the extra shielding,” said Phyl, “we wouldn’t want to come this close.”

“That bad, Phyllis?”

“Very high levels of X-rays and gamma rays. Higher than theory predicts.”

“I guess they’ll have to revise the theory.” She saw a second object, glowing dully nearby. A planet. With an atmosphere. It looked like a moon seen through a haze. “So it does have a companion.”

“Yes, it would seem so.”

IT WASN’T A planet. The thing was a brown dwarf, a star not massive enough to light up. “It’s about eight times as massive as Jupiter,” said Phyl.

“Anything else in the system?”

“Not as far as I can see.”

Hutch took them in closer. Angled them so they were able to look down on the accretion disk. It was a swirl of dazzling colors, of scarlet and gold and white. The ring was twisted and bent, an enormous tumbling river, dragged this way and that by the immense tidal effects, simultaneously brilliant and dark as if the rules of physics shifted and melted in the flow.

Antonio sat beside her, his notebook in his lap. “No way to describe it,” he said.

A light mist was being sucked off the surface of the brown dwarf. It spiraled out into the sky, a cosmic corkscrew, aimed at the black hole, until it connected with the accretion disk.

“It’s feeding the accretion disk,” said Antonio. “That’s what lights it up. If the brown dwarf weren’t there, there’d be no accretion disk.”

“And we wouldn’t be able to see the hole,” said Hutch.

“That’s correct.”

“It’d be kind of dangerous, navigating through here,” she said.

“I’d say so.”

The dwarf writhed like a living creature. “How long will this process take?” Hutch asked. “Before the dwarf collapses and the lights go out?”

“Difficult to estimate. Probably millions of years.”

Hutch was thinking about the physics associated with black holes, how light freezes along the accretion disk, how time runs at a different pace close to the hole, how there’s really nothing there yet it still has enormous mass. There’d been talk in recent years that it might be possible to use antigrav technology to send a probe into a black hole. Rudy had thought it was impossible, that any conceivable technology would be overwhelmed. “How big’s the hole?” she asked.

“Probably not more than a few kilometers.”

Strange. The accretion disk was the most impressive physical object she’d ever seen, majestic, beautiful, overwhelming. Yet she couldn’t see what produced it.

“Hutch,” said Phyl, “the McAdams is in the area.”

THEY RENDEZVOUSED A few hours later. The ships had pulled back well away from the barrage of radiation, and the accretion disk was now only a glimmer in the night.

Hutch and Antonio took the lander over, and, glad for one another’s company, they settled into the common room. Mostly it was small talk, the long ride from Sigma 2711, how it was the end of January and where had the year gone? The latter remark, made by Antonio, had been intended as a joke. It fell flat, but Jon pointed out that Antonio was spending all his time with a beautiful woman, and the next time they tried something like this they should think things out more carefully.

They were looking at telescopic views when Phyl appeared, dark hair this time, dark penetrating eyes, wearing a lab coat, in her science director mode. The room went quiet.

She addressed herself to Hutch. “There’s something odd about the brown dwarf.”

“How do you mean?”

“It has too much deuterium.”

Hutch shrugged. Even Dr. Science looked amused. It was hardly a problem.

Phyl persisted. “It should not exist.”

“Explain, please.”

“Brown dwarfs are normally composed of hydrogen, helium, lithium, and assorted other elements. One of the other elements is deuterium.”

“Okay.”

“Deuterium is a heavy isotope of hydrogen, with one proton and one neutron. It was manufactured during the first three minutes of the Big Bang, and after that production got shut down. You don’t get any more by natural processes. Only small quantities were made initially. So there’s not much of it around. No matter where you look.”

“And this one has too much?” It still didn’t sound like a major issue.

“Yes.”

“What’s normal?”

“Only .001 percent. A wisp. A trace. A hint.”

“And how much does this one have?”

“Half—fifty percent. Well, forty-nine percent actually. But the point is there’s way too much. It’s impossible.”

“I can’t see that it’s a problem for us. Just log it, and we’ll let somebody else crunch the numbers and figure it out.”

“You don’t understand, Hutch.”

“I understand we have an anomaly.”

“No. What you have is an artificial object.”

Hutch wondered if Phyl had blown her programming. “You said it’s eight times the size of Jupiter.”

“Eight times the density.”

“That hardly matters. An object that big could not—”

“Hutch, don’t you see what’s happening here?”

“Not really. No.” She’d felt a lot of pressure since the loss of Rudy. And maybe she wasn’t thinking clearly, but she resented being taken to task by an AI.

“I think I do,” said Jon, who’d been sitting quietly, sipping hot chocolate. “Hutch, anything less than thirteen Jupiter masses is classified as a planet—” He turned to Antonio. “Do I have that right, Antonio?”

“Yes, Jon.”

“Because it never develops sufficient internal pressure to ignite its deuterium, let alone its hydrogen.”

“My God,” said Antonio. “Yet here’s an object eight times Jupiter’s mass. It displays surface abundances that can only come from deuterium burning. That’s impossible with 1/1000th of a percent deuterium. But deuterium ignition works perfectly if the object is born with eight Jupiter masses and fifty percent hydrogen and fifty percent deuterium. All it needs is a spark.”

“Wait a minute,” said Matt. “Would somebody please do this in English? For the slow kids?”

Jon and Antonio stared at one another. Both looked stunned. Jon was rubbing his forehead. “Think of a trace of air,” he said. “Mix it with gasoline and it’s stable. But a mixture of fifty percent gasoline and fifty percent air is highly combustible. A spark is all you need.”

“So where are we?” asked Hutch.

“Hutch,” said Antonio. “Nature can’t make, or ignite, fifty-fifty deuterium-hydrogen objects. So something else must have done it.”

“But why?” asked Matt. “Why would—?” He stopped cold.

“It’s a traffic sign,” said Hutch. “Without the dwarf—”

“Exactly right.” Antonio clapped his hands. “We said it coming in. Without the dwarf, the black hole would be invisible. Somebody just passing through, who doesn’t know in advance it’s there, could get gobbled up.”