Like all good medieval coaching inns, the Green Man in Fareham, Hertfordshire, boasts a resident, if retired, ghost: Dr Thomas Underhill, a notorious seventeenth-century practitioner of black arts and sexual deviancy, rumoured to have killed his wife. The landlord, Maurice Allington, is the sole witness to the renaissance of the malign Underhill. Led by curiosity and an anxious desire to vindicate his sanity, Allington uncovers the key to Underhill's satanic secrets. And the skeletons in the cupboard of Allington's own domestic affairs are just rattling to get out, too.