They were identical in every way

Until the unthinkable tore them apart

Isolte and Viola are twins. Inseparable as children, they've grown into very different adults: Isolte, a successful features writer for a fashion magazine with a photographer boyfriend and a flat in London, and Viola, desperately unhappy and struggling with a lifelong eating disorder.

What happened all those years ago to set the twins on such different paths to adulthood? As both women start to unravel the escalating tragedies of a half-remembered summer, terrifying secrets from the past come rushing back - and threaten to overwhelm their adult lives...