Chapter One Photos were Lucy''s thing. Not so much being in them but taking them, collecting them, looking back on them. Her phone constantly complained about maxed-out storage and she had albums crammed with printed pictures of Adam and the girls. Every social event, every holiday, she''d be reaching for her phone. Not to post the snaps on social media or perfect them with filters, but just to lock in the moments. Adam teased her about it, as did their best friends, Cora and Scott, but Lucy didn''t care. It made her happy. And if she was honest, so did their teasing.

So that was why, when a colleague started showing off her honeymoon pictures at an otherwise mundane work party, Lucy gravitated toward her. She didn''t know it would change her life, would be the difference between seeing and not seeing, knowing and not knowing. She was just drawn in by the blue skies flashing across her colleague''s phone. The small group that had gathered around Ruth shuffled to make room, and Lucy drew up a seat. She loved wedding and holiday snaps in particular, even those of people she didn''t know well. She associated them with joy and sunshine, food and wine-all her favorite things. "Easily pleased," Cora would say with a laugh when Lucy got excited about cherry ice cream on the beach or her favorite Malbec on offer in Sainsbury''s. Lucy would stick out her tongue-"We can''t all find inner peace through yoga and meditation, Cor, some of us get it from snacks and booze and box sets"-and try to persuade her friend to treat herself, too.

Now she stared at her colleague''s pictures of creamy-white sands and shimmering lagoons, and felt a familiar longing for good times, new memories, new photos in her own phone. Sometimes it was as if she couldn''t get enough, was trying to max out her life as well as her iCloud. "It looks absolutely amazing, Ruth," she said with feeling. Ruth taught history and Lucy had always thought of her as ultra-serious-unlike herself, the drama teacher with the infamously loud laugh-but seeing her in the Maldives with her new husband, glowing and relaxed, cast her in a different light. Lucy nudged her plastic chair a little closer. She wasn''t sure why these work gatherings always took place in a classroom, the buffet laid out on the scuffed desks and everybody milling awkwardly. But then, if she was honest, the only socializing she truly enjoyed these days was the evenings and weekends that she and Adam spent with Cora, Scott, and the kids. She felt a yearning whenever she was in anybody else''s company, like she wasn''t exactly where she belonged.

Her mind had started drifting, planning their next joint movie night (what film, what theme, what food?), when she saw an image in her colleague''s hand that tugged her sharply back. "Hang on, Ruth," Lucy said. "Could you. flick back to the previous picture?" Ruth looked surprised but pleased, especially as others had started to lose interest and were chatting among themselves. "Oh, we met this other lovely couple one night while we were there." She swiped back and thrust the phone toward Lucy. The picture seemed to come slowly into focus, everything else receding. For a weird moment, Lucy felt as if she could''ve taken it herself.

She''d captured Scott and Cora in that exact pose many times-arms round each other, heads angled together. At parties, at their vow renewal ceremony, outside the shared Norfolk holiday cottage on the day they''d all picked up the keys. Except this picture, dated only five days ago, wasn''t of them. It was Scott on the right, with his rumpled auburn hair and photogenic features. He wore a green linen shirt with the top three buttons undone, and was smiling beneath seventies-style sunglasses even though the photo had clearly been taken at night, on what looked like a restaurant terrace jutting out over a black sea. But the woman by his side was not Cora. It was someone Lucy had never seen before, her dark eyes shining in an aura of candlelight. Her hair was dark, too, curly and wild, whereas Cora''s was ash-blonde and poker-straight, usually tied in a high bun.

This woman looked slightly older than both Cora and Scott, her face beautiful but very much lived-in, her shoulders hinting at a much sturdier frame than Cora''s petite, yoga-honed body. Lucy could feel Ruth frowning at her in confusion. Her heart was pounding and it took her a while to speak. "A couple?" she said. "Are you sure?" "Ohhh yes! They even gave Martin and me a run for our money in the smoochiness stakes!" Ruth said. "We joked about that when we got chatting to them. We only saw them the once, though, which was odd, given that it was a tiny island. And a shame, too, ''cause they were great fun.

" "How." Lucy''s head felt thick. "What.were their names?" "Jason and Anna," Ruth reeled off with pride. "An interesting pair! Pretty drunk that night, but then so were we!" She laughed to herself, as if at some remembered in-joke, then swiped onward, reeling through more palm trees and lapping waves while Lucy sat back in her chair with bile rising in her throat. *** Her thoughts were a tangle by the time she got home. She walked up the overgrown path and into the usual chaos of the hall: Tilly''s purple bike on its side, blocking the way; shoes of various sizes overflowing from the rack. In her distraction, she put her foot on a tennis ball that had been abandoned in the middle of the floor and almost went flying.

She snatched it up, cursing to herself, squeezing it like a stress reliever as she made her way through to the kitchen. Adam was preparing homemade pizzas. Always their Friday-night treat, with more and more ambitious toppings each week-Lucy would joke that the only area of his life in which he took crazy risks was cooking. There was no sign of Tilly or Fran. Their green school bags hung from the backs of two chairs, probably harboring important letters or forgotten homework instructions that Lucy would have to sniff out later. For once, she was glad the girls weren''t in the room, rushing toward her with kisses and complaints and anecdotes from their day. She wanted to talk to Adam about the photo. All the way home, she''d been trying to think of plausible explanations.

Maybe the woman was a work friend of Scott''s. He was away on business at the moment-though supposedly in Japan, not the Maldives. He organized air shows and other aerospace events all around the world and often traveled. Perhaps the Maldives was also part of this trip, and Ruth had got the wrong end of the stick about his relationship with a colleague? Maybe she''d got it wrong about the names, too? Jason and Anna. A run for our money in the smoochiness stakes. The floor seemed to tilt beneath Lucy''s feet each time she remembered those words. "Where are the girls?" she asked as Adam kissed her in an entirely non-smoochy way, holding flour-covered palms out to his sides. His glasses were smeared and he was wearing the floral apron Lucy had been given in a work Secret Santa two years ago and had never actually worn herself.

Distractedly, and out of habit, she slipped his glasses off his face and wiped them for him on a clean corner of the apron. "In the garden," he said as she slid them back on, "playing some incomprehensible variation of tag with Ivy and Joe." Lucy stilled. "Ivy and Joe are here?" It wouldn''t normally have come as a surprise. Most weeks, they were here more often than they weren''t. But today it sent Lucy into a mini panic. And she realized Cora and the kids hadn''t been around as much while Scott had been away, as if all their routines had been thrown out by his trip, things changing already, coming apart at the seams. "I picked them up from school, too," Adam said.

"Cora''s got a meeting and Scott''s not back ''til later tonight. Cor should be here soon, though. I said her and the kids could join us for pizzas. I just hope I''ve not made this dough too"-he squinted at his handiwork, prodding it with his thumb-"well, doughy." Lucy stepped closer to Adam, laying a hand on his arm. "Ad, I saw something really strange today." "Did you?" He glanced at her, still preoccupied by the consistency of his pizza bases. Lucy gazed through the big kitchen window at the kids playing in the garden, moving around each other in a dance of utmost familiarity and absorption.

So comfortable together, so accepting of Tilly''s bossiness and Fran''s left-field imagination; Ivy''s primness and the way Joe''s voice got too loud when he was excited by a game. Lucy''s heart strained. She often worried about the day they might grow out of one another, grow out of wanting to spend so much time within their two-family unit, especially as Tilly approached secondary school and they all got taller by the week. But now a new fear overwhelmed her, one she''d never imagined having to face. What would happen if an upset as big as an affair tore their lives down the middle? "I saw a photo," she said breathlessly. "Of Scott in the Maldives.with another woman." Adam spluttered out a laugh that sent flour particles whirling.

" What? " His amusement was almost comforting. It spoke of how ridiculous the idea was. Lucy grasped at the hope that they would all chuckle about this misunderstanding in a few days, when everything had been cleared up and explained away. "My colleague-you remember Ruth?" She barely paused for his response because he was terrible at remembering people and names, always marveling at how she recalled (and obsessed over) endless details.