The key
(Book)

"1956. It is Ellen Crosby's first day as a student nurse at Ambergate Hospital. When she meets a young woman admitted by her father, little does Ellen know that a choice she will make is to change both their lives for ever (sic). 2006. Sarah is drawn to the now abandoned Ambergate. Whilst exploring the old corridors she discovers a suitcase belonging to a female patient who entered Ambergate fifty years earlier. The shocking contents, untouched for half a century, will lead Sarah to unravel a forgotten story of tragedy and lost love, and the chance to make an old wrong right."--cover.