Tell Me Where You Are by Moira Forsyth

Maybe the worst thing hadn't happened yet. You couldn't know the awful things lined up in the future, looming. The last thing Frances wants is a phone call from Alec, the husband who left her for her sister thirteen years ago. But Susan has disappeared, abandoning Alec and her daughter Kate, a surly teenager with an explosive secret. Reluctantly, Frances is drawn into her sister's turbulent life.
Binding: Paperback / softback