First published in 1977, it features Fraser's sleuthing heroine Jemima Shore as she revisits the convent school where she was educated following the mysterious death of one of the nuns.

A six-part television dramatisation of the book (written by Julia Jones) was part of ITV's anthology series Armchair Thriller in 1978.

The tower and the ancient history of the Order are recorded in the Treasury of the Blessed Eleanor, a manuscript that is referenced throughout the story.

Patsy Kensit, then just nine years old, plays one of the convent schoolgirls, Tessa Justin, who has a significant role in the final two episodes.

[1] Network released Armchair Thriller on DVD in 2008, both in separate volumes for each story and as an 11-disc set featuring all of the episodes produced by Thames Television.