Mostly Dead Things tells the story of Jessa-Lynn Morton, who takes over her father’s taxidermy business shortly after his suicide. Still grieving, she struggles to keep both the business and her family from falling apart. While Jessa buries herself in work and alcohol, her mother begins making lewd window displays with animals from the taxidermy shop. Jessa's first love—also her brother Milo’s wife—ran out on the family years before, leaving Milo with their young daughter and her troubled son from a previous relationship. Struggling to cope with her absence, Jessa and Milo remain locked in a pattern of resentment and grief.