Sisters Chelsea and Ronnie Benson haven't spoken to each other in two years. When their mother announces she wants the whole family to go on a week-long holiday in Lanzarote for her sixtieth birthday, both dread the excursion for different reasons. Sophisticated singleton Chelsea, a fashion journalist, would rather not revisit the "chips with everything" world she left behind when she moved to London. Ronnie, now a mother of two, is feeling fat and frumpy: the last thing she wants is to strip down to a swimsuit alongside her super-thin, super-chic sis. The week begins badly and gets worse, as underlying tensions and secrets are exposed. And then their mother drops a bombshell on the group. Will the holiday bring the sisters closer, or blow the Benson family apart?