We all have that friend – the one who doesn’t quite belong. Dinah Marshall is that person & knows it. After someone drops out, she’s invited to spend the weekend at a luxury holiday home with women she’s known since university. However, the gulf between them has widened, & Dinah is conscious of being the only one with no money, career, partner or children. Feeling like an outsider, she takes to snooping around the house. She’s fascinated by its owners, Sarah & Isaac Rivers – & when she finds she can secretly stay an extra night, that fascination quickly spirals into obsession. When Isaac Rivers meets ‘Diana Malone’ at an exclusive members club, he introduces her to his wife & friends, & she’s soon welcomed into the group. She seems to be trying a little too hard, & as her somewhat intense behaviour starts to raise eyebrows, one of her new acquaintances begins to suspect she isn’t who she says she is.