‘She lifted the flap of the envelope and pulled out the single white page. As she opened it up she stared, open mouthed. Four words were typed on the page. I am watching you.'

When Amy Whyte and Penny Brogan leave a local nightclub in the early hours of Sunday morning and don't arrive home, their families are beside themselves with worry. Conor Dowling has just been released from prison, a man full of hatred for Amy, the girl who put him behind bars in the first place.

The case is given to Detective Lottie Parker, when the girls' blood-soaked bodies are found, days later, in a derelict squat. Chillingly, both girls are clutching silver coins in their hands – what message is this killer leaving behind? All the signs point to Conor but his alibi is water tight.

As Lottie examines Penny and Amy's final days alive in a desperate search for clues, two more girls are found stabbed to death in a luxury apartment complex. Caught up in what is fast becoming her toughest case yet, Lottie is unaware that somebody is watching her every move.

Then Lottie's two daughters, Katie and Chloe suddenly disappear from the town centre. Terrified that the killer has her girls, the stakes have never been higher for Lottie.

But as Lottie puts everything on the line to find her daughters and solve the case, she's about to find herself in terrible danger – someone has a personal axe to grind with her and they know the best way to get to her is to hurt the ones she loves the most.

Her shoes pinched as she shivered in the cold night air. She just wanted to get home. A taxi slowed to a halt next to her, and as she buckled her seat belt, she noticed the child's seat next to her and felt safe. But when she saw his eyes in the mirror, a shiver of terror shook her to her core…

When a young woman's body is found on a patch of wet grass in the early hours of the morning, Detective Lottie Parker mourns the young life so brutally snatched away. Looking at the victim's flimsy strappy top, damp from the dew and soaked with blood, it is clear that this young girl never came home from a night out. Lottie's heart breaks as she thinks of the girl's parents finding their daughter's empty bed and she vows to catch the murderer.

The young woman is soon identified as Laura Nolan, and Lottie watches the blood drain from her mother Diana's face when she tells her the terrible news. Diana reveals that Laura was on a date the night she was killed, but she doesn't know who with… and Laura's empty bedroom with make-up scattered across her dressing table offers no clues.

Lottie and her team rush to trace Laura's last moments. But hope at a potential breakthrough turns to horror for Lottie when another young woman, Shannon Kenny is reported missing, last seen climbing into a taxi with a broken light, close to the same bar.

But then, Lottie discovers a connection between Laura and Shannon that totally overturns everything she thought she knew. The killer didn't stalk these two young women at random. He knew exactly who they were and where they would be. But can Lottie stop him before he strikes again?