Merve Emre’s new book begins like a true-crime thriller, with the tantalizing suggestion that a number of unsettling revelations are in store. Early in “The Personality Brokers: The Strange History of Myers-Briggs and the Birth of Personality Testing,” she recalls the “low-level paranoia” she started to feel as she researched her subject: “Files disappear. Tapes are erased. People begin to watch you.” Archival gatekeepers were by turns controlling and evasive, acting like furtive trustees of terrible secrets. What, she wanted to know, were they trying to hide?

It takes a while to realize that Emre has gotten you hooked under arguably false pretenses, but what she finally pulls off is so inventive and beguiling you can hardly begrudge her for it. The revelations she uncovers are less scandalous than they are affecting and occasionally (and delightfully) bizarre. Emre, a professor of English at Oxford, wrote a previous book on the surge of readers in postwar America, and she knows that a story is inextricable from how it’s told. “The Personality Brokers” is history that reads like biography that reads like a novel — a fluid narrative that defies expectations and plays against type.

Considering her subject matter, Emre’s heterodox approach is appropriately perverse. The Myers-Briggs Type Indicator (M.B.T.I.), for the uninitiated few, is an “instrument” — the word “test” is verboten by the center that distributes it — designed to assess personality in terms of four dichotomies: extraversion (E) or introversion (I); sensing (S) or intuition (N); thinking (T) or feeling (F); and judging (J) or perceiving (P). Corporations use it for personnel management; colleges use it for guidance counseling; individuals use it for self-help.

Books like Annie Murphy Paul’s “The Cult of Personality” (2004) have examined the M.B.T.I.’s insidious social effects, but in “The Personality Brokers,” it’s more like a MacGuffin, the device that sets the plot in motion. Emre doesn’t trust it; nor does she trash it. It is, she suggests, as idiosyncratic and as fallible as we all are.