When Elizabeth's husband dies, leaving her with crippling debt, the only person she can turn to is her friend, Jo. Soon Jo has called in her daughter, Lucy, to help save Elizabeth from bankruptcy. Leaving her old life behind, Lucy is determined to make the most of her fresh start. As life slowly begins to return to normal, these three women, thrown together by circumstance, become fast friends. But then Jo's world is turned upside down when she receives some shocking news. In search of solace, Jo and Elizabeth find themselves enjoying midnight dips in the freezing Irish Sea.

Celebrating her forty-fifth birthday at her local pub, popular podcaster Alix Summer crosses paths with an unassuming woman called Josie Fair. Josie, it turns out, is also celebrating her forty-fifth birthday. They are, in fact, birthday twins. A few days later, Alix and Josie bump into each other again, this time outside Alix’s children’s school. Josie has been listening to Alix’s podcasts and thinks she might be an interesting subject for her series. She is, she tells Alix, on the cusp of great changes in her life.

The sudden death of a pupil in Fleat House at St Stephen’s—a small private boarding school in deepest Norfolk—is a shocking event that the headmaster is very keen to call a tragic accident. But the local police cannot rule out foul play and the case prompts the return of high-flying Detective Inspector Jazmine ‘Jazz’ Hunter to the force. Jazz has her own private reasons for stepping away from her police career in London, and reluctantly agrees to front the investigation as a favour to her old boss.

Minnie Cooper knows two things with certainty: that her New Year's birthday is unlucky, and that it's all because of Quinn Hamilton, a man she's never met. Their mothers gave birth to them at the same hospital just after midnight on New Year's Day, but Quinn was given the cash prize for being the first baby born in London in 1990 - and the name Minnie was meant to have, as well. With luck like that, it's no wonder each of her birthdays has been more of a disaster than the one before.

Gemma Robinson comes into Elliot’s life like a whirlwind, and they marry and settle into his home. When she asks him if her parents can come to stay for a couple of weeks, he is keen to oblige - he just doesn’t quite know what he’s signing up for. The Robinsons arrive with Gemma’s sister, Chloe, a mysterious young woman who refuses to speak or leave her room.

It was supposed to be the perfect reunion: six university friends together again after twenty years. Host Ali finally has the life she always wanted, a career she can be proud of and a wonderful family with her college boyfriend, now husband. But that night her best friend makes an accusation so shocking that nothing will ever be the same again.

Samantha Frayn doesn’t know why Peter Bridges picks her - a nobody with bitten fingernails and a troubled childhood behind her - but she falls quickly. He’s older, charming, likes fine wine and French films, and his beautiful home has real art on its walls. Peter transforms Samantha’s life in an instant. He sees the better version of herself - the one she’s always wanted to be. It’s only normal that there’s a little friction, when she moves in, over domestic matters like where things are kept, or the proper times to eat, sleep, and shower.

Alice Raikes takes a train from London to Scotland to visit her family, but when she gets there she witnesses something so shocking that she insists on returning to London immediately. A few hours later, Alice is lying in a coma after an accident that may or may not have been a suicide attempt. Alice’s family gathers at her bedside and as they wait, argue, and remember, long-buried tensions emerge. The more they talk, the more they seem to conceal. Alice, meanwhile, slides between varying levels of consciousness, recalling her past and a love affair that recently ended.

When Mimi Huish visits her dad at his new home in the Cotswolds, she immediately falls in love with the eccentric and charming inhabitants of his new community. And when she meets the seriously gorgeous, charismatic Cal Mathieson, Mimi begins to daydream about trading in her city life for country living. But even though Mimi and Cal feel like they might be soul mates, fate (and bad timing) keeps pulling them apart.

It’s summer in the city and passions are soaring along with the temperature - for everyone but Mitchell Fisher, who hates all things romance. He relishes his job cutting off the padlocks that couples fasten to the famous “love story” bridge. Only his young daughter, Poppy, knows that behind his prickly veneer, Mitchell still grieves the loss of her mother.

Charlotte Morgan knows how it feels to desperately want a baby. As a child, seeing her mum devastated by losing her longed-for babies, Charlotte wished another woman could give her mother what she so craved. Now Charlotte’s a mum herself and knowing how much love her daughter, Alice, brings into her life, she vows to help others achieve their dreams of becoming a parent. When she meets Malcolm and Brenda on a surrogacy website, it seems she's found the perfect couple. In their late 40s, they have wealth and an enviable life, but there’s one thing missing – a child of their own.

In 1997 teenager Sophie White and her three girlfriends decide they want to lose their virginity before summer is over. Roping in her childhood buddy Gareth and his mates, Sophie holds a party to get the deed over and done with, but the night doesn’t end as planned. Twenty years later, the group are brought back together when Gareth is killed in a car accident and Sophie begins receiving threatening messages. It seems the party wasn’t as innocent as everyone thought, and now someone wants payback.

One mother's past could cost her everything. Frankie Keegan is struggling. While she tries to make strides in her career, life at home is slowly unravelling as she is haunted by the secrets of her past. Someone else remembers. As the dark nights draw in, the anniversary of the loss of her brother looms, and Frankie is drawn back to the memories of that fateful night 20 years previously. As she descends into a guilt-ridden state, she begins to suspect that someone else is also remembering that night and they are determined to terrify her.

In seven days, Maggie’s son, Max, turns three. But she’s not planning a party or buying presents or updating his baby book. She’s dreading it. Because in her world, third birthdays are the days on which the unthinkable happens...she loses her child. For the last 12 years Maggie has been imprisoned in a basement. Abducted aged 15, she gave birth to two sons before Max, and on their third birthdays her captor came and took them from her. She cannot let it happen again. But she has no idea how to stop it. And the clock is ticking....

There's Bella, stay-at-home mum of Teddy. She suffered postpartum psychosis after Teddy's birth. There's Chrissy, divorce lawyer, married to Russell. They're having some problems with their sex life. There's Electra, mother to twins, who is struggling with her son's behaviour. There's Skye, a single mother, who used a sperm donor to have her baby. Then there's Jen. She was supposed to be a mother, but it hasn't worked out like she expected.