The Book of Lost Things by John Connolly

Connolly weaves an amazing tale of a young boy who has lost his mother to cancer. Set in England shortly as a World War threatens to ravage the countryside, David's father eventually remarries and David gets a new sibling. David suffers from Obsessive Compulsive Disorder, developed during his Mother's lengthy battle with cancer. After his mother's death, his mental condition worsens. He begins to experience blackouts, and stranger still...he can hear books whispering to him.
He withdraws from his family, and one night sets out from his house to examine a plane crash in a nearby garden. As he makes his way deeper into the trees, he leaves our world behind, finding himself trapped in a land of fairy tales. These aren't friendly Disney characters, these are monsters and flawed beings from the original tales of the Brothers Grimm. David travels across the land in search of a King, who he is convinced can put everything right. Along the way, he must flee from wolves, join a band of seven dwarves (who've never been given such hilarious backstories). He is shadowed by the nefarious Crooked Man, the spirit of all things evil. He must learn what it means to be brave, and to stand up for his family if he hopes to get out alive.
At the end of young David's story, Connolly adds a coda of sorts, an extremely moving tale that takes place over a scant few pages, wrapping up an amazingly told modern fairy tale. Highly recommended.