The story focuses on high school occultist, Andromeda, who simultaneously tries to save her beloved local library from modernization and solve the various mysteries surrounding: her missing much-older boyfriend; the strange signs seemingly being sent to her from her recently deceased best friend Daisy; and her ever more prophetic tarot readings.

She is unattractive, hard of hearing, her best friend and former magical partner Daisy recently died of cancer, "St. Steve" her boyfriend has gone missing, her mother is completely overbearing and her father is a paranoid conspiracist.

However, in this process, she picks up Byron, a short guy with unfortunate facial hair who nevertheless becomes a kind of apprentice to Andromeda's occultism, and confidant as new, exciting, but generally confusing text messages suddenly start coming in from St. Steve.

The story gathers pace as Andromeda's tarot readings become increasingly literal and prophetic, sparking interest from fellow students, eager to know their futures, and more pressingly, who their boyfriends are cheating on them with.

[4] Portman has reported that a planned promotional visit to a school in a Portland, Oregon area was cancelled due to "parental worries about the occult elements" in Andromeda Klein.