Languishing in a dungeon cell of Syria's then-ruler Bashar al-Assad, an unknown prisoner scrawled a verse of Arabic poetry on his cell wall — an expression of pain and love amid his torment.

as Ms. Miano now depicts in “Twilight of Torment: I. Melancholy,” the first part of a somber two-volume work. The novel centers on the Mususedis, a well-to-do coastal clan that descends from a ...