I nominate "Echoes from the Dead" by Johan Theorin
Review from Amazon:
"Twenty years ago Julia Davidsson's 5-year-old son Jens disappeared into the fog on the remote Swedish island of Íland and was never found. Everyone except Julia believes Jens wandered down to the shore and drowned. Unable to accept that her son is dead, Julia withdraws from her family and stumbles through life using alcohol and medication to deaden the pain of not knowing. Then, after all these years, her father Gerlof calls to tell her that someone has sent him one of Jens's sandals in the mail; so Julia returns to Íland to try, once again, to find her son.
Johan Theorin's "Echoes from the Dead" is an absorbing mystery that works on several levels: as a classic whodunit that keeps the reader guessing up to the last few pages, as a horror story with scenes that slowly pull the reader reluctantly forward, and as a family story that examines how tragedy cuts at the ties that bind and leaves them hanging by fragile threads. It is a story that unfolds across and between time periods starting with the day Jens disppears, then flowing back and forth between present and past: from Gerlof at the nursing home holding Jens sandal in his hand to before World War II where we pick up the life of Nils Kant, who supposedly died and was buried long before Jens disappeared but who Gerlof suspects is somehow involved in his grandson's disappearance. Above all, the novel is the story of a landscape, the island of Íland, that Theorin presents as a central character with a life and history of its own--a landscape that interacts with all its human inhabitants and drives their behaviors. "