McKinsey & Co. is the global fix-it firm of choice, whether you’re a company looking for an outsider to justify laying off thousands of employees or a government looking to get its managerial act together. A new book by Duff McDonald, a contributing editor at Fortune and The New York Observer, provides a good history of the firm but can’t seem to decide whether McKinsey is a valuable advisor or a waste of money.

I reviewed “The Firm: The Story of McKinsey and Its Secret Influence on American Business,” for Bloomberg Muse today. You can read it here.