The Silence by Susan Allott

In London, Isla Green gets a phone call from her father in Sydney. He tells her that the police have questioned him about a neighbor who went missing thirty years ago. She decides to return to Australia because she can sense that her father, with whom she's always been close, needs her. Isla remembers the neighbor, Mandy, because Mandy babysat Isla when Isla was young. The Silence tells the story of Isla's parents and Mandy and her husband, Steve, in the late 1960's when they lived next door to each other, along with the contemporary story of Isla trying to uncover what happened to Mandy three decades ago. A great choice for those who like books about family relationships with a suspenseful edge.