The Leaves Forget — Alan Baxter

Olivia has been missing for months. Her family have tried to accept that perhaps she'll never be found, and they'll never know what happened. So when her brother Craig unexpectedly receives a stack of letters from Liv, all written not long after her disappearance, he's both excited and frightened. Reading through her correspondence, Craig begins to get a sense of where she was, but he still doesn't know where she is now, or if she's still alive. Using what clues he can from the old letters, Craig sets off with his partner and his father to find Olivia, hoping for the best, fearing the worst.