Books like The Invisible Ones

Rose Janko is missing. It has been seven years since she disappeared, and nobody said a word. Now, following the death of his wife, her father Leon feels compelled to find her. Rumour had it she ran off when her baby boy was born with the family's genetic disorder. Leon is not so sure. He wants to know the truth and he hires a private investigator to discover it - Ray Lovell. Ray starts to delve deeper, but his investigation is hampered by the very people who ought to be helping him - the Jankos. He cannot understand their reluctance to help. Why don't they want to find Rose Janko?