So now Ring A and the spine were both controlled by people calling themselves the stayers. No one who might want to free Aram and Freya and Badim and their four companions could come anywhere near the infirmary in Kiev.

Instead, the antagonists were now separated by locked doors. And sixteen people in Ring B were dead, killed either when hit by objects, or when cut or impaled, or when trampled by crowds. Another ninety-six people were injured. All the infirmaries in Ring B soon were filled with hurt people, and the medical teams in them were completely overwhelmed. Eighteen more people died in the following hours as a result of their injuries. The streets of San Jose were covered with wreckage and pools of congealing blood.

The bad times had returned.

In the infirmary in Kiev, Freya and the others had had their wristpads and other communicators taken from them, which they obviously found shocking. Khetsun still had an earbud that he had hidden when he was being searched, and listening to it, he relayed what he heard of the news of the fighting to the others with him in that room.

Freya said, “With all that going on, I think we can escape these people here. They’re sure to be distracted.”

“How?” Aram asked.

“I know a way back to Ring B. Euan taught it to me.”

“But how will we get out of this building?”

“It’s just an ordinary room. I don’t think the locks or the doorjambs, or the doors, were made to stop someone from breaking them. These assholes are probably relying on guards to keep us in here, and the guards may be off dealing with this other stuff.”

“The engineer’s solution,” Aram said.

“Why not?”

“Good question.” Aram put his ear to the door and listened for a while. “Let’s try it.”

They took apart a bed frame in the room and used its footing to strike the doorknob. Forty-two strikes, and the doorknob broke off; another sixty-two strikes, mostly made by Freya, broke the door latch assembly out of the doorjamb and the door swung open.

“Quick,” Freya said. As they hurried down the hallway outside the room to a stairwell, a young man came out of another room and yelled at them to stop. Freya walked up to him saying, “Hey, we were just—” and then punched him in the face. He fell back into the wall and slid to the floor, and though he tried to get up, he was too groggy to succeed. Freya leaned over and tore his wristpad off his wrist, then led the others into the stairwell, where they descended to an exit onto the street outside. People had congregated at the screens outside a dining hall near the Great Gate of Kiev, and Freya and the others ran the other way, toward the lock leading to Mongolia and the end of Spoke Two.

The lock door leading up to Spoke Two was closed.

The Steppes biome was as far from Nova Scotia as one biome could be from another. Aram and Tao were in favor of them trying to make their way around Ring A to Tasmania, where they had friends in the eucalyptus forest they thought would take them in.

Freya insisted they make for home. “I know the way,” she said. “Follow me.”

She led them into Mongolia, and near the wall next to Spoke Two, she went to a little herder’s shed with its slate roof, which she had visited nine years before in an excursion with Euan. She tapped out a code on the doorpad. “Euan knew to make it my name, so I wouldn’t forget,” she said as she typed, and then the lock released, and inside the shed she got the others to help her move aside the big flagstones in the middle of the floor. “Come on, they’ll be after us soon, and we’ll be putting out a signal, I wouldn’t doubt they have trackers on us somewhere, not to mention this wristpad. Does anyone have a sweeper we can use to check?”

No one did.

“So we’ll just have to be fast. Come on.”

Under the flagstones was a narrow dark tunnel that after a U-turn and rise led to a vent in the wall of Spoke Two. None of them had lights with them, but Freya judged it best that they move the flagstones back into place and walk in the resulting darkness, slightly lit by the wristpad of the unfortunate man who had gotten in their way. By its light they shuffled along the tunnel until they came to the vent cover in Spoke Two, where Freya unscrewed the backing of the vent cover and they stepped out into the Spoke Two passageway.

From here they ran up the spiral staircase that adhered to the walls of all the spokes’ main passageways, to the bulb of little storage rooms clustered around the inner ring where it intersected Spoke Two. Freya again led them to a door, and tapped in a code on the doorpad, then led them inside.

When they were inside and the door was closed, Freya had them sit on the floor and rest. They had run hard up Spoke Two’s stairs.

“Okay, the next part is difficult,” she told the others. “The support struts between the inner rings aren’t meant to be passageways, but they’re hollow now that the fuel they carried is gone, and there’s a utilidor running next to the fuel bladder that is really narrow. It’s full of bulkheads, but Euan and his gang broke all the locks in this strut. So we should be able to get to Inner Ring B’s Two station through it, and from there go down to Nova Scotia.”

“Let’s go then,” Khetsun said.

“Sure. But watch out for the bulkhead footings. This is where we’ll really wish we had better light. Just step carefully.”

They got up and took off again, progressing through the narrow utilidor of the strut by the light of the stolen wristpad. The utilidor was only three meters in diameter, and often the space was filled by a narrow catwalk, also braids of cables, and various boxes. The struts connecting the inner rings were so close to the spine that the gravity effect of the ship’s rotation was not as strong as out in the torus of biomes, and so they had to step carefully to avoid launching themselves up into the metal ceiling, or the upper frames of the bulkhead doorways. In the dim light of Freya’s stolen wristpad, and the black shadows its beam created, it was not easy, and they were not very fast, nor were they quiet. It took them well over an hour to get along the strut.

Finally they came to the last door, which opened onto Inner Ring B’s Two station, and found it was locked. For a moment they stood there silently regarding the doorpad in the light Freya was shining on it. It did not look like a door they could break down, and they didn’t have anything much with which to try that.

Finally Freya said, “Can anyone list the prime numbers?”

“Sure,” Aram said. “Two, three, five, seven—”

“Wait,” Freya interrupted. “I need you to go up through the primes by primes, if you see what I mean. Give me the second prime, then the third, then the fifth, then the seventh, and on like that. I think I need seven of them that way.”

“Okay, but help me.” Aram paused to collect himself. “The second prime is three, third prime is five. The fifth prime is eleven, the seventh is seventeen. The eleventh is… thirty-one. The thirteenth is… forty-one. The seventeenth is… fifty-nine, I think. Yes.”

“Okay, good,” Freya said, and pushed the door open. “Thank you, Euan,” she said, and a spasm crossed her face that left her looking furious.

She opened the door lightly, and they listened as well as they could, trying to determine if anyone was in the little complex of storage rooms comprising Inner Ring B’s intersection with its Spoke Two. They couldn’t hear anything, but didn’t know what that meant; Freya couldn’t remember if in the old days they had ever eavesdropped on people from within the utilidor or not.

But all their caution went for nothing, as the door was opened from the other side and they were ordered to come out. They looked to Freya, who appeared poised to flee, but then one of the people in the station pointed something at them, something that by its shape alone announced its purpose, even though none of them had ever seen one before except in photos: a gun.