Rest Not In Peace

"Is there reason to suspect evil in this?" I asked. 

"None... but that the man was robust one day and a corpse the next." 

Master Hugh, surgeon and bailiff, has been asked to provide a sleeping potion for Sir Henry Burley, a friend and guest of Lord Gilbert at Bampton Castle, near Oxford. Three days before St John's Day, in the year of our Lord 1368, Sir Henry went to his bed hale and hearty after enjoying a long evening music, conversation, and dancing in Bampton's Castle's hall. The next morn his valet found him cole and dead. 

Master Hugh is asked by Lord Gilbert to determine the cause of death - despite shrill accusations from Sir Henry's grieving widow...