Psychiatrist Dr. Gwen Moore is an expert on killers. She’s spent a decade treating California’s most depraved predators and unlocking their motives - predators much like the notorious Bloody Heart serial killer, whose latest teenage victim escaped and then identified local high school teacher Randall Thompson as his captor. The case against Thompson as the Bloody Heart Killer is damning - and closed, as far as Gwen and the media are concerned. If not for one new development.

Dannie Kohan lives her life by the numbers. She is nothing like her lifelong best friend - the wild, whimsical, believes-in-fate Bella. Her meticulous planning seems to have paid off after she nails the most important job interview of her career and accepts her boyfriend’s marriage proposal in one fell swoop, falling asleep completely content. But when she awakens, she’s suddenly in a different apartment, with a different ring on her finger, and beside a very different man. 

For 15 years, Lexi and Jake have played the same six numbers with their friends. Over drinks, dinner parties and summer barbecues, the three couples have discussed the important stuff — kids, marriages, careers — and they’ve laughed off their disappointment when they failed to win anything.

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....

Shelby Tebow is the first to go missing. Not long after, Meredith Dickey and her six-year-old daughter, Delilah, vanish just blocks away from where Shelby was last seen, striking fear into their once-peaceful community. Are these incidents connected? After an elusive search that yields more questions than answers, the case eventually goes cold. Now, 11 years later, Delilah shockingly returns. Everyone wants to know what happened to her, but no one is prepared for what they'll find....

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. 

Ten years ago he killed my son. Today I married him. Ten years ago my darling son Jesse was murdered and our perfect family was destroyed. My strong, handsome boy, so full of life, became a memory, a photo I carried with me everywhere. But today I’m finally close to finding happiness again. My ash-blonde hair has been curled into ringlets. Carefully placed white flowers frame my delicate features. The small, drab chapel has been prettied up with white satin, and there are tiny red hearts scattered on the small table where I will soon sign the register with my new husband. 

Lily hasn't always had it easy, but that's never stopped her from working hard for the life she wants. She's come a long way from the small town in Maine where she grew up - she graduated from college, moved to Boston, and started her own business. So when she feels a spark with a gorgeous neurosurgeon named Ryle Kincaid, everything in Lily's life suddenly seems almost too good to be true.

Daisy and Simon’s marriage isn’t what it seems…. After years together, the arrival of longed-for daughter Millie sealed everything in place. They’re a happy little family of three. So what if Simon drinks a bit too much sometimes — Daisy’s used to it. She knows he’s just letting off steam. Until one night at a party things spiral horribly out of control. And their happy little family of three will never be the same again.

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.

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? 

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 is Erin’s 40th birthday party. Pink and silver balloons drift through her garden, the platters of food are empty and the recycling is overflowing with empty wine bottles. Erin mingles with groups of family and friends, surrounded by love and laughter. Then a little red envelope lands on the doormat and everything changes. Inside is a birthday card from somebody she never dreamed would get in touch. Its message is a chilling reminder of the dark past that Erin has worked so hard to bury, a past that could put her precious family in terrible danger....