Father Figure by Emma Forrest

Gail is in trouble at school. Saint Saviours, the exclusive private girls school that she attends on a scholarship, cannot contain her. Impulsive, bored and looking for someone to adore, she is at that dangerous age when you want to be picked up by men and then driven home by your mother. Ezra is rich, powerful and at the top of his game. His comfortable middle age is tainted only by the knowledge that, in his heady youth, he'd loved new wave music and had people killed - and by his crushing anxieties about his teenage daughter, Agata. When Agata starts at Saint Saviour's, Gail and Ezra's paths cross, and with an unstoppable momentum, their lives intertwine in ways more dangerous than either could ever predict.