Nina Stibbe’s “Reasons to Be Cheerful” is so dense with amusing detail that I thought about holding the book upside down to see if any extra funny bits might spill from the creases between the page.

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.