Have your read Room by Emma Donoghue? What about Still Missing by Chevy Stevens? Both of these are very good books and while they are definitely NOT a series, I recommend you read Still Missing before you read Room. If it's too late for that, read both anyway. Emma Donoghue lives in Great Britain while Chevy Stevens (a pseudonym - who would have guessed?), lives in British Columbia. I'm pretty sure the authors probably don't even know each other; however these books work wonderfully together.
Both of these great reads deal with abduction. I think they should be read in a certain order because Still Missing is about a twenty-something real estate agent who get kidnapped. She is held captive in a remote location by her abductor for several years. Despite her efforts to retain herself, she is forced to comply with his odd quirks in order to survive. As a result, both her mind and her body become brainwashed. I won't spoil a good read by giving away too much, but eventually she manages to escape. Then she has to find herself and discover who she is now because, as you can imagine, this event has totally changed her and her perception of herself. The story is told from the viewpoint of the kidnapped woman through a series of sessions with her psychiatrist as she is trying to heal.
Room deals with abduction from the viewpoint of a five year old son of a woman who was abducted and has been a prisoner for years. For the boy, the room he lives in with his mom is the world and it is all he has ever known. The beautiful thing about this narration is the matter-of-fact way he describes his world with his mom, including visits from his father, whom he only sees through slats in a wardrobe because his mom is determined to protect her son from her abductor. As the boy gets older, his world becomes smaller and eventually his mother figures out way to save them both. She has to learn how to live in the real world again and he has to learn that the world is bigger than the room he knew.
I read Still Missing before I read Room completely by accident. I had never heard of either book before. However, as I was reading Room I was able to superimpose and understand the unspoken viewpoint of the mom because of Still Missing. Emma Donoghue's writing from the viewpoint of the five year old boy was brilliant. His innocence and his normal, childlike acceptance of his life enables her to write of unimaginable events in a matter-of-fact way. While the reader intuitively understands and gets hints of his mom's experience, as I was reading Room the woman in Still Missing became the boy's mother. I enjoyed both books more fully because I read them in order and I am sure you will too!