Tony Ramsay's play is a darkly comic detective story set against a background of witchcraft in Elizabethan Norfolk. Billy Rainbow is an actor on the London stage. Following a little difficulty involving a butcher's wife from Wapping, he is persuaded to go to the country and reprise his stage role as an unmasker of devils on the the estate of Sir Edmund Ferrule - where the locals have been troubled by an apparent spate of Satanism.