As Nick and Nora Charles in the six Thin Man movies from 1934 to 1947, the husband-and-wife team of William Powell and Myrna Loy showed that marriage didn’t have to mean the end of the romantic comedy. From the comedic delight that was the initial The Thin Man through its five sequels as well as eight other films (including the Oscar-winning The Great Ziegfeld and Manhattan Melodrama), Powell and Loy were cemented in the public imagination as Hollywood’s happiest married couple. In Becoming Nick and Nora, comedy writer and Hollywood historian Rob Kozlowski follows the winding path that...