Marigold Finch boards a train headed to the mysterious Chekhol Institute, a secret academy devoted to preserving "forbidden books deemed too dangerous for society". This institute is filled with eccentric rich-kid scholars known as Archivists – a group gifted with the creative power and training needed to enter story worlds and live inside them. Marigold knows that her brother Sebastian, who disappeared a few years ago, was accepted to the same archivist program before he went missing. When she discovers that Sebastian has been trapped inside an unfinished mystery novel called The Hampton Inheritance, Marigold ventures inside to save him before it's too late.