Ten years ago, Theodora “Teddy” Angstrom’s older sister, Angie, went missing. Her case remains unsolved. Now Teddy’s father, Mark, has killed himself. Unbeknownst to Mark’s family, he had been active in a Reddit community fixated on Angie, and Teddy can’t help but fall down the same rabbit hole. Teddy’s investigation quickly gets her in hot water with her gun-nut boyfriend, her long-lost half brother, and her colleagues at the prestigious high school where she teaches English. Further complicating matters is Teddy’s growing obsession with Mickey, a charming amateur sleuth who is eerily keen on helping her solve the case. As she struggles to reconcile new information with old memories, Teddy’s erratic behavior reaches a fever pitch, but she won’t stop until she finds Angie.