Rebecca Carter and her daughter Monica, nicknamed Moonflower, travel the American West, always on the move, always hiding, always looking behind them, always keeping Moonflower out of sight.
They speak to no one, only interacting with people when it's absolutely necessary.

But wherever they go, bodies are left behind.

Special Agent Marc Donner of the FBI has been tracking a killer for the best part of two years. A murderer that strikes once every few weeks.

The victims are all men, many disappearing only to be found months later, dumped in forests or rivers or quarries, far from their places of death. All of them with their throats opened, their bodies bled out and their spinal cords severed.

The killer leaves no trace, no clues only a trail of corpses.

After all this time, Donner has gleaned only a handful of facts from the few witnesses and snippets of CCTV footage available. He's hunting a middle-aged woman who drives a van with blacked-out windows and false plates.

Often she poses as a child online to lure in her prey. It's never been enough to track her down though.

Until now.

And so begins a cat-and-mouse game between Donner and his prey, Rebecca and Moonflower. But who is the actual hunter and who is the actual prey? For perhaps Moonflower isn't the child that her mother claims she is.

Perhaps she's something else and as Donner puts everything on the line to capture them and prove his suspicions right, perhaps he isn't prepared to face what is really out there.

Let the Right One In meets Stephen King in this chilling thriller about a mother's love, a daughter's devotion, a man's obsession and the darkness that lives within us all.