Emily and Jake are the perfect couple. Or so everyone says. But Emily just read a letter that has shattered her perfect world. Now she only has one thing on her mind. Which one of her friends is sleeping with her husband?

I return home to our beautiful house on a chilly winter evening expecting to find my handsome husband Richard waiting for me by the fire. We’re still so in love, and he always takes care of me. He usually comes straight back from work. But tonight, our antique clock ticks on through the dark evening, with no sign of him. Then a knock at the door shatters my perfect life. A 12-year-old-girl, Alice from the village, has been found unconscious in the field behind our house. They say she was last seen getting into Richard’s car.

Gen is on the verge of a divorce from her cheating husband. When her sister, Meg, has a convention to attend in the Big Apple, she invites Gen along to celebrate her newly found freedom. But the perfect sisters’ getaway quickly goes awry when a tipsy Gen defiantly throws her wedding ring off the hotel room’s balcony. Then, wanting some fresh air, she decides to take a late-evening walk alone and vanishes without a trace.

When I arrive unannounced at my husband's studio in need of a shoulder to cry on after hearing that my best student, Alex, has died, I see a pair of wineglasses drying by the sink, and my deepest fear is confirmed: my husband is having an affair. Most women would fall to their knees in tears and throw him out of the house - but I just can't bring myself to do it. Instead, I go home and cook a healthy dinner for our children, walk the dog, and unload the dishwasher without complaint. I need this marriage to work to protect a terrible secret of my own....

Fran finds her standing by the swings. A little girl, Esther, no older than seven years old, by herself in the dead of night, her pretty but old-fashioned yellow dress covered in grass stains and her hair dishevelled. She says she's waiting for Father, and that strikes Fran as particularly odd. After Esther is reunited with her family, Fran can't stop thinking about this pious child whose imaginary friend is God. Fran's instincts tell her something is very wrong. Why does Esther keep running away from home, and how did she get that bruise on her leg? 

No relationship is perfect. But since the birth of baby Mabel seven months ago, Amber and George have been in desperate need of a night away. Mabel is all that Amber has ever wanted, but she can’t deny that sometimes she struggles to cope. George has booked them into a luxury hotel, and Amber’s sister is babysitting. Yet just as they are ready to leave, Amber can’t suppress a feeling of worry.... 

Hannah has done everything to make sure her life is safe and secure. A long way from her unstable childhood growing up in foster care, she’s content with her sweet, little, messy apartment and her satisfying job as a social worker. She quietly worries that, aged 36, she might never fall in love. But otherwise her life is where she wants it to be. Until, encouraged by her best friend to join a dating app, she meets Alex. He’s irresistibly handsome. He loves the same music as her. The same food as well. 

Ava only left her daughter in the pushchair for five minutes. The buckle was fastened, and she was sure it was safe. But when she came downstairs, the door was open and Abi was gone - she walked down the road, past the Lovegoods' house, and was never seen again. A year later, the Lovegoods throw a housewarming party, showing off the results of their renovation. Ava doesn’t want to go. She can’t bear to look down that end of the road, to see the place where Abi vanished, and she doesn’t want to spend time with people who don’t share her grief. 

Pete Riley answers the door one morning and lets in a parent's worst nightmare. On his doorstep is Miles Lambert, a stranger who breaks the devastating news that Pete's son, Theo, isn't actually his son - he is the Lamberts', switched at birth by an understaffed hospital while their real son was sent home with Miles and his wife, Lucy. For Pete, his partner Maddie, and the little boy they've been raising for the past two years, life will never be the same again.

It was supposed to be the happiest day of her life. Zoe was sitting in her hotel room, in her perfect white dress, looking forward to the moment when she would make kind, handsome Toby her husband. Then, there was a blank. They said she must have fainted, overcome with emotion. But nothing felt quite right afterward. Did something happen in that missing time? 

When she was 9 years old, Melody Browne's house burned down, and it took all of her childhood memories with it. Now she's a single mother of a teenage boy living in Central London. She hasn't seen her parents since she left home at 15, but she doesn't mind. She's better off on her own. She works as a dinner lady at her son's school and has no idea where her humdrum life is heading. But one summer's night, a hypnotist inadvertently unlocks memories of her childhood, and her whole life is turned upside down.

What was my sister doing standing over Florence’s cot in the middle of the night?I trust my sister, Carrie, with my daughter’s life. But then she’s accused of a terrible crime. Carrie lives under our roof, she pushes my daughter on the swings, she takes her out for ice cream. You might ask, why do I let her? Why would I risk my darling baby? How could I let my sister stay? Because I have a dangerous secret too. One that only Carrie knows about. And if that secret gets out, I could lose my little girl....

You're not who you say you are. Neither is she. She thinks she knows me. She believes my marriage is falling apart at the seams, that my husband can barely look me in the eyes. She thinks I’m desperate for a baby, that my longing for a family keeps me up at night. As much as I hate to admit it, all of this is true. She thinks I listen to her advice, that I care about her opinion. That couldn’t be further from the truth. Because she has no idea who I am. She has no clue that I know everything. I know her secret. I know that she did the unforgivable. I know how many lives she ruined.

Cassie stares at the woman on her doorstep in disbelief. Just months after losing her only son, Josh, here stands a stranger claiming to be Josh’s girlfriend. But it’s not only the woman Cassie is shocked by, it’s the baby nestled in Kim’s arms. Cassie’s grandchild. I know what you did. As Cassie tries to do what’s best for baby Samuel, she starts to receive threatening messages from someone from her past - someone Cassie has been hiding from for a long time.

Selena Murphy is commuting home on the train when she strikes up a conversation with a beautiful stranger in the next seat. The woman introduces herself as Martha and soon confesses that she’s been stuck in an affair with her boss. Selena, in turn, confesses that she suspects her husband is sleeping with the nanny. When the train arrives at Selena’s station, the two women part ways, presumably never to meet again. Then the nanny disappears.