The Mezzanine tells this story through the extensive use of footnotes—some of them comprising the bulk of the page—as the narrator travels through his own mind and past.

The Mezzanine is essentially plotless, a stream-of-consciousness fiction that examines in detail the lunch-hour activities of young office worker Howie, whose simple lunch (popcorn, hot dog, cookie and milk) and purchase of a new pair of shoelaces are contrasted with his reading of a paperback edition of Marcus Aurelius's Meditations.

Baker's digressive novel, partly composed of extensive footnotes of up to several pages in length, follows Howie's contemplations of a variety of everyday phenomena, such as how paper milk cartons replaced glass milk bottles, the miracle of perforation, and the buoyant nature of plastic straws; and of everyday objects such as vending machines, paper towel dispensers, and popcorn poppers.

Critics cited Baker's trademark style of highly descriptive, focused prose, his "fierce attention to detail," and his delight in portraying discrete slices of time within the frame of mundane existence.

"[2] New Yorker writer Laura Miller[3] praised Baker's "dazzling descriptive powers married to a passionate enthusiasm for the neglected flotsam and jetsam of everyday life.