U.S. Rep. Elise Stefanik has referred multiple times to her new book as her “first,” implying more to come. For her next, I hope she tells the dramatic tale of her extraordinary political transformation and the dead end to which that ultimately led. The youngest woman ever elected to the House of Representatives, Stefanik started out as the “model moderate millennial,” in the words of a New York Times profile. Her mentor was the establishment Republican Paul Ryan. With the rise of Donald Trump, establishment Republicans had to make a choice. Ryan — then a still youthful speaker of the...