By Helen Wan, St. Martin’s Press, 294 pages, $25.99

To Mark Twain has been ascribed the saying, “All you need in this life is ignorance and confidence, and then success is sure.” Whether his aphorism was uttered tongue-in-cheek might be debatable; that it would never find its way into a “statement of principles” at Parsons Valentine & Hunt LLP, the fictional white-shoe law firm in first-time author Helen Wan’s “The Partner Track” is anything but, as there the measure of success for aspiring young associates is defined by a singular, objective achievement: partnership.