Twenty years ago, Abigail Sorenson’s brother, Robert, went missing one day before her 16th birthday, never to be seen again. That same year, she began receiving scattered chapters in the mail of a self-help manual, The Guidebook, whose anonymous author promised to make her life soar to heights beyond her wildest dreams. The Guidebook’s missives have remained a constant in Abi’s life --- through her family’s grief over her brother’s disappearance, a move across continents, the devastating dissolution of her marriage, and the new beginning as a single mother and café owner in Sydney. Now, two decades after receiving those first pages, Abi is invited to an all-expenses-paid weekend retreat to learn “the truth” about The Guidebook.