Grace, Meg and Daphne, all in their 70s, are minding their own business while enjoying a cup of tea in a café when 17-year-old Nina stumbles in. She's clearly distraught and running from someone, so the three women think nothing of hiding her when a suspicious-looking man starts asking if they've seen her. Once alone, Nina tells the women a little of what she's running from. The need to protect her is immediate, and Grace, Meg and Daphne vow to do just this. But how? They soon realise there really is only one answer: murder. And so begins the tale of the three most unlikely murderers-in-the-making, and may hell protect anyone who underestimates them.