The opening scene is perfection. We meet the eponymous heroine of Diane Johnson’s latest novel, “Lorna Mott Comes Home,” as she rides in the back of a taxi, en route to the train station in Lyon.

The assignment: Craft a novel from the literary equivalent of found objects. Consider the narrative possibilities contained not just in letters and e-mails, but in school report cards, emergency room bills and police reports filed by night managers at Westin Hotels.

The rules of shelving can seem arbitrary, even arcane, but the fundamentals are easy to learn: two hard covers, and no more than three paperbacks of the same title, on each shelf.  The exception is the face-out. If the jacket is displayed horizontally, behind it you can stack as many books as can fit.