A Burnable Book and The Invention of Fire by Bruce Holsinger are a set of mysteries set in London in the 1380s. The main character is John Gower, a poet, a buyer and seller of secrets and a good friend of Geoffrey Chaucer. In each book he faces a crime that threatens to throw his carefully balanced city into chaos and violence. These books capture the feeling of daily life in a medieval setting better than anything I've ever read in the era.