The author suggests that the time in a person's life between 20 and 29 are critical to the growth and development of personal character, career, relationships, and if avoided as a result of thinking that 30 is the new 20, risks drastically reduced career prospects, relational and child-bearing potential, and character deficit.
Intersperced with aggregate biographies of clients of her psychological therapy practice who fit the 20-something demographic and are experiencing identity, career, or relationship stasis, the book raises important questions that balk at the current ideology of considering the 20s as a time for exploration, freedom, not tying yourself down with decisions, and avoiding the restrictions of having relationships, career, or children.
The work section raises the concept of "identity capital", encompassing skills and experience that benefit long term career and explaining why a internship at an animation company that leads to a career in cinematography is a better role than a barista at a coffee shop even though both may pay similarly initially (or the internship less or nothing). I did find the concept a bit strained though in not encompassing the broader character development and non-career skills that make someone successful at home and in kinwork. As of yet in the book, the pattern of a working partner and a homemaker partner seem to be untalked about with respect to what "identity capital" means for someone not persuing a career.