While Downton spends a lot of time on World War I and its fallout, The Halcyon takes place a few decades later, at the height of World War II. Set at a five-star London hotel, it has many of the same upstairs/downstairs tensions as Downton, with the staff of the hotel and their wealthy guests both getting time in the spotlight. The hotel, owned by a rich family of aristocrats, is the site of forbidden romances, society scandals, family drama, and political conspiracies as the staff and guests struggle with the new reality of a Britain at war again.