The seemingly simple investigation of the death of a cathedral organist leads Professor Gervase Fen, idiosyncratic Oxford don and amateur detective, into a complicated case involving butterfly collecting, international espionage, witchcraft and a Nazi plot.

The seemingly simple investigation of the death of a cathedral organist leads Professor Gervase Fen, idiosyncratic Oxford don and amateur detective, into a complicated case involving butterfly collecting, international espionage, witchcraft and a Nazi plot.