Justina Robson 
Down to the Bone [EPUB ebook] 
Quantum Gravity Book Five

Lila Black faces her greatest challange yet as she takes herself, her dead lover and the AI in her head into death’s realm.The Quantum Gravity series, set in a world where our reality mixes with other dimensions that are the homes to Faeries, elementals and demons, is unique in modern SF — a series that is willing to incorporate legend, myth and magic while maintaining a rigorous approach to scientific and pyschological reality.And in Lila Black Justina Robson has created an enduringly strong yet quirkily human and flawed heroine.