Set in the near future, Afterparty explores a world where psychoactive drugs are printable. All you need is a chemjet printer and an Internet connection to begin printing designer drugs on paper, which is torn up and digested for each hit. The story follows Lyda Rose, one of the five founders of Little Sprout, a group trying to find a cure for schizophrenia, a condition from which Lyda's mother suffered.
The group is successful and Numinous is ready for trials when an event changes their lives. In high enough doses, Numinous permanently alters the user's perception by imprinting a bond with whatever god they believe in, often paired with hallucinations of a holy figure to watch over or even run their lives. Lyda believed the recipe was off the market, but then someone shows up in her ward who is clearly under its effect.
Angered by this, Lyda leaves care early with plans to find the source. With help from a few friends, not all of them real, she goes on a thrilling adventure across Canada and the United States in search of answers.