Excerpt from Instructions for a Heatwave by Maggie O'Farrell, plus links to reviews, author biography & more

Highbury, London

The heat, the heat. It wakes Gretta just after dawn, propelling her from the bed and down the stairs. It inhabits the house like a guest who has outstayed his welcome: it lies along corridors, it circles around curtains, it lolls heavily on sofas and chairs. The air in the kitchen is like a solid entity filling the space, pushing Gretta down into the floor, against the side of the table.

Only she would choose to bake bread in such weather.

Consider her now, yanking open the oven and grimacing in its scorching blast as she pulls out the bread tin. She is in her nightdress, hair still wound onto curlers. She takes two steps backwards and tips the steaming loaf into the sink, the weight of it reminding her, as it always does, of a baby, a newborn, the packed, damp warmth of it.

She has made soda bread three times a week for her entire married life. She is not about to let a little thing like a heatwave get in the way of that. Of course, living in London, it is impossible to get buttermilk; she has to make do with a mixture of half milk and half yogurt. A woman at Mass told her it worked and it does, up to a point, but it is never quite the same.

At a clacking sound on the lino behind her, she says, "Is that you? Bread's ready."

"It's going to be—" he begins, then stops.

Gretta waits for a moment before turning around. Robert is standing between the sink and the table, his large hands upturned, as if he's holding a tea tray. He is staring at something. The tarnished chrome of the tap, perhaps, the runnels of the draining board, that rusting enamel pan. Everything around them is so familiar, it's impossible sometimes to tell what your eye has been trained upon, the way a person can no longer hear the individual notes of a known piece of music.

"It's going to be a what?" she demands. He doesn't reply. She moves towards him and places a palm on his shoulder. "You all right?" She has, of late, been finding herself reminded of his age, the sudden stoop of his back, the look of mild confusion on his face.

"What?" He swings his head around to look at her, as if startled by her touch. "Yes." He nods. "Of course. I was just saying it's going to be another hot one today."

He shuffles sideways, just as she'd known he would, towards the thermometer, which clings, by a spit-moistened sucker, to the outside of the window.

It is the third month of the drought. For ten days now the heat has passed 90ºF. There has been no rain—not for days, not for weeks, not for months. No clouds pass, slow and stately as ships, over the roofs of these houses.

With a metallic click, like that of a hammer tapping a nail, a black spot lands on the window, as if pulled there by magnetic force. Robert, still peering at the thermometer, flinches. The insect has a striated underside, six legs splaying outwards. Another appears, at the other end of the window, then another, then another.

"Those buggers are back," he murmurs.

Gretta comes to see, jamming on her glasses. Together, they peer at them, transfixed.

Swarms of red-backed aphids have, in the past week, been passing over the city. They mass in trees, on car windscreens. They catch in the hair of children coming home from school, they find their way into the mouths of those crazy enough to cycle in this heat, their feet adhere to the sun-creamed limbs of people lying in their back gardens.

The aphids fling themselves from the window, their feet detaching at the same moment, as if alerted by some secret signal, and they disappear into the azure sky.

Gretta and Robert straighten up, in unison, relieved.

"That's them gone," he says.

She sees him glance at the clock on the wall—a quarter to seven. At precisely this time, for more than thirty years, he would leave the house. He would take his coat off the peg by the door, pick up his bag, call goodbye to them all, shouting and squawking in the kitchen, and slam the door behind him. He always left at six forty-five, on the proverbial dot, no matter what was happening, whether Michael Francis was refusing to get out of bed, whether Aoife was kicking up a stink about Godknowswhat, whether Monica was trying to take over the cooking of the bacon. Not his department, all that, never was. Six forty-five, and he was out the door, gone.

Excerpted from Instructions for a Heatwave by Maggie O'Farrell. Copyright © 2013 by Maggie O'Farrell. Excerpted by permission of Knopf, a division of Random House LLC. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.