Rest Not in Peace by Mel Starr

Master Hugh is asked to provide a sleeping potion for Sir Henry Burley, a friend and guest of Lord Gilbert at Bampton Castle. Sir Henry, (with his wife, a daughter by a first wife, two knights, two squires, and assorted servants), has outstayed his welcome at Bampton Castle. The next morning after Master Hugh provides the potion, Sir Henry is found dead, eyes open, in his bed. Master Hugh, the target of the wife's wrath, is asked by Lord Gilbert to determine the cause of death ...