Vietnamese culture and religious traditions place the utmost importance on dying well: in old age, body unblemished, with surviving children, and properly buried and mourned. More than five million people were killed in the Vietnam War, many of them young, many of them dying far from home. Another 300,000 are still missing. Having died badly, they are thought to have become angry ghosts, doomed to spend eternity in a kind of spirit hell. Decades after the war ended, many survivors believe that the spirits of those dead and missing have returned to haunt their loved ones.

In War and Shadows, the anthropologist Mai Lan Gustafsson tells the story of the anger of these spirits and the torments of their kin. Gustafsson's rich ethnographic research allows her to bring readers into the world of spirit possession, focusing on the source of the pain, the physical and mental anguish the spirits bring, and various attempts to ameliorate their anger through ritual offerings and the intervention of mediums. Through a series of personal life histories, she chronicles the variety of ailments brought about by the spirits' wrath, from headaches and aching limbs (often the same limb lost by a loved one in battle) to self-mutilation.

In Gustafsson's view, the Communist suppression of spirit-based religion after the fall of Saigon has intensified anxieties about the well-being of the spirit world. While shrines and mourning are still allowed, spirit mediums were outlawed and driven underground, along with many of the other practices that might have provided some comfort. Despite these restrictions, she finds, victims of these hauntings do as much as possible to try to lay their ghosts to rest.