When Kate moves to London after the disappearance of her sister, she's in need of a friend. A chance meeting leads Kate to Della, a life coach who runs support groups for young women, dubbed by Kate as 'the Janes.'

Della takes a special interest in Kate, and Kate soon finds herself entangled in Della's life - her house, her family, and her husband. It's only when she realises that she's in too deep that Della's veneer begins to crumble, and the warnings from 'the Janes' begin to come true.

Why is Della so keen to keep Kate by her side? What does Kate have that Della might want? And what really lies beneath the surface of their friendship?