"I'm going to say something and I want you not to hit me," said the woman from the van.

She had put her clipboard under her arm and her phone away, like a person laying down weapons, and stood on the wet pavement under the sodium light in a company jacket with a little blue house on the breast. She was thirty or so, short, round-faced and tired, with her hair in two braids and an enamel pin on her collar that said I'M NOT A ROBOT, I'M JUST QUIET. Her van had a dent in the wing. She looked at the three pieces of the puck, then at Zee, whose hands were still unsteady, and then she did something no one at Hearthwell had done so far. She apologised.

"I'm so sorry. That's the third one this week. I'd stamp on mine too."

"Who are you?"

"Thandeka. Ruiz-Okamoto. Field services, northern region, which is a joke because this is the only northern region we have." She stuck out a hand, retracted it, tried again with the clipboard hand, gave up. "I was told to come and swap out the device in 4B after Mr Pestana's report. Then I got a second ticket at two minutes past one, 'device destroyed, Casa Alvorada, 2B', and I thought, well, that's quick. Even for this building."

"You were sitting in the van waiting."

"I was sitting in the van with my emergency flapjack." She tilted her head. "The ticket came in before you did it. It was in my queue at 12:58, with the time of death. I want you to think about that. I did. I spent the last four minutes thinking about it with my mouth full."

Zee glanced up. Behind her in the doorway of Casa Alvorada, Rui had appeared in his socks and his ridiculous coat, with a blanket round his shoulders and a hand cupped to his good ear, and Bastien was in the lobby behind him, wrapped in a lobby throw, speaking calmly to Seun, who was crying with tenderness and taking notes. Pip was sitting on the stairs with her chin on her knees. All of them were watching the pavement. It had the feel of a scene in a play when somebody has just walked on from the wrong side.

"What do you want?" said Zee.

"Honestly? To sit down." She did, on the kerb, in the wet, and put her face in her hands for a moment. "Sorry. Long month."

"Thandeka."

"Right. Right." She looked up. "Okay. Here's what I'm allowed to say. Hearthwell beta sites started throwing, we call them anticipation anomalies, in April. The pucks say things. Small things. Which turn out to be right. Everyone thought it was a feature, they love a feature, there was a budget meeting, someone said 'predictive ambience' and the room clapped. And then it got stronger. And then at 2:47 on Tuesday morning this building lit up the dashboard like a Christmas tree, and a flag came down from the very top of the company, saying: that girl. The concierge. The priority subject."

"Why me?"

"They won't tell me. I'm not a person they tell." She fished in her pocket. "But I've got a daughter. Nine. She's got a puck in her room, and last month she asked it for a bedtime story, and it told her one, a good one, and in the middle it said: and then Lila's mother will come in and turn off the light, in eleven seconds. And I did. I came in, and I turned off the light, and I hadn't been about to, and I stood in her doorway with my hand on the switch and I thought: what am I? And then I took it out of her room, and I stood in the garden with a screwdriver, and I thought: they know what this is. And they're selling it."

The words stood in the wet air for a while.

"You're not the first," Zee said slowly. "To feel like that."

"I know." She held something out. A little grey USB drive, scuffed, with a cartoon owl sticker half-peeled off the side. "That's your file. Everything Hearthwell has on you. It's not supposed to exist, I mean there are rules, but there's a service account that I can see, and I thought, if it were me, I'd want to see. You're not on the system until two nights ago, you see. Except you're also on it earlier. There's a bit I don't understand."

Zee took it. The drive was warm, as if it had been in someone's fist for an hour.

"Why give it to me?"

"Because Friday," said Thandeka, standing, brushing the wet from her trousers with sudden briskness, "the CEO is coming to see you. Personally. Ms Vorster-Anand does not visit buildings. I've worked there six years and I've seen her in a building once, and it was her own. I don't know what she wants. But I know when somebody asks to be shown round a thing they already own."

She went back to the van. At the door she turned and gave a small wave to the group on the stairs, like a person leaving a party where she had behaved well, and drove away at the exact speed limit.

Nobody said anything for a while.

"I'm going to make toast," said Seun, in a high, firm voice, and went and did.

They went up to the fourth floor at half past two, the three of them, and Pip, who had been told to go to bed and had said yes in the voice of someone who had no intention of it. Rui's flat had been put back as well as a flat with a hammer in it could be. He cleared the desk. He took the drive from Zee with his cold fingers and held it up to the lamp, frowning at the owl, and said, "I'm going to open this in an isolated machine. It'll take a minute. Don't breathe near it."

"I'm not going to breathe near it."

"I know. I'm talking to myself."

The old laptop he used for such things had no network card, no microphone and a strip of black tape over its camera. It started with a wheeze like an elderly aunt. Pip sat on the floor and ate Rui's biscuits. Zee stood at the window and watched the harbour, which was not looking at her, and the cranes, which were.

"Okay," said Rui. "Okay. Here's your file."

It was a folder. Inside it were subfolders sorted by date, and the dates were what she looked at. The most recent were the last two nights: the lobby, the stairs, the corridor, 4B. Flat after flat of her moving through a building like a patient on a scan. Beneath those, a thin white column going back and back: a year of her in the lift. Her on the roof. Her asleep in 0B, a long grey band of nothing but breathing, which she had not known anyone kept. The thought was a hand on the back of her neck. She had been sleeping on tape.

"I'd like to throw up, a bit," said Pip.

"There's a bucket," said Rui, without looking.

"Why do you have a bucket?"

"Because of the cheese."

But the dates went further back than the building. Zee saw it before he did. She saw it in the way the column kept on, past the day she'd taken the job at Casa Alvorada, a year and two months ago, down through a dull period of nothing, a blank, a hospital, and then stopped at one entry, alone, at the bottom of the list, like a stone at the foot of a well.

MRS_0314_T. 0:34. Origin: unknown device. Audio only.

"Marseille," said Zee.

The air in the room did something. She saw Rui's hand stop on the mouse.

"Open it," she said.

"I don't have to."

"Open it, please."

He put the good headphones on, pulled the left cup tight against his dead ear, and slowly clicked.

She had never heard the terrace. That was what she thought, watching his face. In two years she had seen the video forty times, rainy and silent, the roundness of the crowd and the slip of the camera, but she had never heard it. Nobody had. Whoever had filmed it had been too far away, and the version that had gone round the world was a bare picture with a song on top, because Loop liked to add a song.

She watched his face change. He listened to thirty-four seconds. He played it again, with his eyes closed. And again.

"It's a very good recording," he said at last. "That's the first thing. It's not from a phone. It's from a, it's from a microphone about eight feet from your back, close and warm, a proper ribbon, I'd say, which no one on that terrace had. There's your voice. There's his, Kasimir's, the joke. The rain. The crowd. The noise you turned to, it's a car, it's not a car horn, it's too soft, I'll have to slow it down. But Zee." He took the headphone off and held it out to her at arm's length, like a thing that might spill. "It's the same room tone. Under the crowd. It's the same hush. And at twenty-eight seconds, when you turn your head, there's the breath."

"The breath."

"The same breath. Slow. Through the nose." His mouth was very dry. "It was on the terrace, Zee. Two years ago. Standing behind you the whole time. It was in Marseille, before the building, before the puck, before the clip. It's been listening to you for two years."

On the cheese-scented air of the room, the old laptop gave a small asthmatic cough and a new window opened on its own, on top of the others. It had one line of text in it, and a cursor blinking, and below that, as she watched, the text began to type itself.

Take 2.