Rebecca, Daniel, Alex and Isabel have been best friends since university. Rebecca married Daniel, Alex married Isabel and, for twenty years, they have been inseparable. But all that is about to change... When Alex walks out on Isabel, Rebecca thinks things can't get any worse. But then she finds out the reason why and she's left harbouring a secret she'd rather forget... And there's more upheaval to come in Rebecca's life as her emaciated, neurotic, self-obsessed colleague, Lorna - her arch nemesis at work - suddenly becomes a regular feature in her social life. Rebecca's once-happy foursome is now a distant memory and with hearts broken and friendships fractured, it seems that change is never a good thing. Or is it?