When the tomb of St Tancred is opened, no one expects to find the body of the organist, lying in a pool of blood, his handsome features covered by a gas mask. Eleven-year-old Flavia de Luce is intrigued.

Why would anyone want to kill the much-admired organist in such a brutal and bizarre fashion? Why place his body in the tomb? And what happened to the remains of the previous occupant?

The mystery leads Flavia deep into the past, to a strange story of lost manuscripts and ancient relics...