A French nun is asked to investigate a Catholic school in Iceland that has been anonymously accused of abusing some of its students.  At the center of these allegations is the school’s headmaster.  Coincidentally, while the investigation is going on, the headmaster dies after falling from the church’s bell tower.   Twenty years later, the same nun is asked by the Vatican to return to Iceland to finally decide if these accusations are true.

The Sacrament is a good read and a fine mystery.  However, there is a lot of jumping around in time, which sometimes was confusing.