The Treacle Well — Moira Forsyth

Caroline and Daniel are twins whose mother died when they were babies. They grow up in a conventional family, their aunt and uncle raising them along with their own little girls, but they are truly close only to each other. Then, their father remarrying, they're separated for the first time and sent to boarding school. A serious accident when they become medical students seems to end without damage to either, but soon after Daniel and Caroline cut themselves off from the rest of the family, causing first bewilderment, then hurt and anger. Underneath the stable family life their grandparents worked so hard to establish, run currents of insecurity and restlessness, and a secret only one person is able to uncover. The novel explores belonging and not belonging, guilt and atonement.