When I pulled the used copy of Empire: The Life, Legend, and Madness of Howard Hughes out of its white plastic mailer it felt oddly light for a book of its girth, its center of gravity not exactly where a hardcover’s ought to be. I turned it over in my hands and opened the cover to discover that the book was hollow. Its middle had been meticulously extracted, leaving a rectangular cavity in which a previous owner had inlaid a thin cedar box. It was beautifully done—perfect corners, no sign of glue.

I’d been spending the pandemic writing a…