Seventeen-year-old Aimee Roh has Sensory Time Warp Syndrome, a rare condition that causes her to time travel back to a moment in her life when she smells something linked to that memory. Her dad is convinced she'll simply grow out of it if she tries hard enough, but Aimee's fear of vanishing at random has kept her from living a normal life. When Aimee disappears for nine hours into a memory of her estranged mom--a moment Aimee has never remembered before--she becomes distraught. Not only was this her longest disappearance yet, but the memory doesn't match up with the story of how her mom left--at least, not the version she's always heard from her dad. Desperate for answers, Aimee travels to Korea, where she unravels the mystery of her memories, the truth about her mother, and the reason she keeps returning to certain moments in her life. Along the way, she realizes she'll need to reconcile her past in order to save her present.