Present day. Dutch archivist Fenna van Wijk is helping architect Ned Thompson to sift through a stack of ancient papers kept in an untouched archive in an old English manor house in Lincolnshire. Among manuscripts dealing with the holy Gilbert of Sempringham, they discover a letter from 1275, written by Eleanor de Montfort, the young bride to be of Welsh prince Llywelyn ap Gruffudd. During their research, Fenna stumbles upon a mysterious child: Gwenllian. The English king Edward I had this infant locked away for ever in a cloister in ... Sempringham. When Fenna and Ned try to understand this harsh decision, they find more than they bargained for.