Missing May is a novel about a girl named Summer who, after living with various uncaring families, is eventually adopted by her Uncle Ob and Aunt May. Living with them in the Appalachian mountains, she feels at home. When May dies, however, Ob is grief-stricken and attempts to contact her dead soul through a medium. After Ob learns that the medium has just died, he turns around, deciding to keep living and take care of Summer.
The novel is set in present-day West Virginia. The protagonist is Summer, an orphaned child who has been passed from one apathetic relative to another. At age six, she meets her Aunt May and Uncle Ob. The kindly old couple notices that, although Summer is not mistreated, she is virtually ignored by her caretakers and decide to take Summer home to their rickety trailer home in the hills of the Appalachian mountains. Summer thrives under their care, feeling that she finally has a home.
Six years after Summer moves in, Aunt May dies suddenly in the garden. Summer must cope with her own grief while worrying about Uncle Ob, who is overwhelmed by the thought of living without his beloved wife. Uncle Ob decides to try contacting May's spirit, after he experiences the sensation that she has tried to communicate with him. He is assisted in this endeavor by Cletus Underwood, a classmate of Summer's, who provides information on a supposed spirit medium of some renown. Summer views his ideas with some skepticism, but is willing to try anything that might alleviate her uncle's sorrow. The three take a roadtrip to meet with the medium, only to discover that she had recently died. Uncle Ob is initially crushed by this news, and Summer fears that this disappointment was the last blow to his will to live. However, on the return trip, Uncle Ob suddenly snaps out of his depression, deciding to continue living on for Summer's sake.