Read Chapter 1: — BEFORE CHRISTMAS

Ravensbridge looked beautiful from a distance.

The old shopping quarter had been dressed for Christmas for weeks: strings of white lights between the stone buildings, red bows above the department-store doors, brass stars hanging over Market Street. Normally, on the last Friday before Christmas, the pavements would have been almost impassable.

Tonight there were gaps.

Ethan Cole noticed them because he drove for a living when he was not at the office. He was not a full-time private-hire driver, but he kept the app on his phone and took jobs on his way home to cover petrol and, as Maya liked to joke, fund his addiction to buying presents for everybody twice.

He was carrying three shopping bags when his phone vibrated.

MAYA: Did you remember the cranberry sauce?

ETHAN: Yes.

MAYA: And the coffee for Dad?

ETHAN: Yes.

MAYA: And not the terrible one you bought last year?

Ethan stopped beneath a shop awning and laughed into his mask.

ETHAN: I have grown as a man.

He had bought the coffee, the cranberry sauce, two boxes of shortbread, chocolates for both sets of parents, a toy for Maya's cousin's baby, and enough cheese to make the boot of their car smell like a farm shop for the drive north.

They were meant to leave in two days.

His parents lived outside York. Maya's mother and stepfather were less than an hour away. Christmas had become an elaborate operation since the wedding: Christmas Eve with one family, Christmas Day lunch with the other, Boxing Day split between both, then friends, cousins and a long argument over who had eaten the last mince pie.

They loved it.

That afternoon, however, Ethan's office had closed early. His department head had gone to hospital with a fever and a dry cough. The official email called it "a precaution". Nobody believed the word.

On his way to the car park, Ethan accepted a fare. A young woman climbed into the back seat wearing a surgical mask and spent the whole journey arguing softly with someone on the phone.

"I know it's Christmas, Mum. I know. But I can't just leave them short-staffed. No, don't put Oliver on—Mum, please."

At the destination, she thanked Ethan and disappeared into a block of flats before he had time to think about what she had said.

Across the road was a chemist.

He bought cold medicine, paracetamol, hand sanitiser and, after a moment's hesitation, the last two respirator masks behind the counter. There were also five boxes of ordinary medical masks. He bought those too.

"Planning for the apocalypse?" the young cashier asked, trying to sound cheerful.

"Planning for Christmas with my in-laws. Same thing."

She laughed, but only for a second.

At home, Maya was standing over a pan of stew when he came up behind her and wrapped both arms around her waist.

"You smell like winter," she said.

"You smell like dinner. I win."

They ate at the small table by the window, talked about the drive, presents, family and whether they were ready for children. Maya was thirty and had recently stopped taking contraception. They had promised each other not to turn trying for a baby into a project.

"If it happens, it happens," Ethan said, stealing one of her roast potatoes.

"You say that because nobody asks you every Sunday whether your biological clock is ticking."

"My mother asks me whether I've checked the tyre pressure. We all have burdens."

Maya kicked him lightly under the table.

After dinner they hung lights in the window. Outside, Ravensbridge glittered through the glass.

Somewhere beyond the river, an ambulance siren rose and faded.

Neither of them paid much attention.