At 2 a.m. on the morning of her 40th birthday, Sophie wakes in the darkness of her bedroom, and finds a stranger watching her from the foot of her bed. The intruder hands Sophie a letter and issues an ultimatum: the message is to be opened at her forthcoming party, in front of gathered family and friends, at exactly 8 p.m. Any failure to comply will not end well. Sophie can only think of one person who hates her enough to have hired a professional to menace her like this: her fiancé's ex-wife. But what can the letter possibly contain? And why must it be read in front of everyone she loves best? This will be no ordinary 40th party. Sophie is not the only person holding a secret about the evening ahead. When the clock strikes eight, the course of several people's lives will be altered forever.