Joan Colby (Ann Harding) is the unmarried older daughter in a once-wealthy family. She's always been the mature, level-headed one among the two sisters, but she is feeling the pressure to find a husband especially strongly these days, as her much more flighty and impetuous younger sister Valerie (Lucille Brown) is about to marry. Joan has been lately seen in the company of John Fletcher (William Powell), the wastral heir to a once-great shipping company -- he doesn't care a bit about the family business, but still has enough money to live an upper-class lifestyle without worry, and is a well-known playboy, and enjoys Joan's company. With her sister's help and the unwitting participation of her well-meaning father (Henry Stephenson), Joan manages to set up a situation in which John is forced to do what they used to call "the decent thing" and marry her. Joan is secretly torn by guilt about how she got his name, however, and tries to be a truly good wife for John over the months that follow -- she gets him to clean up his life a bit, and to take himself more seriously and look past the next game of polo, and even starts to convince him to take more of a role in his family's moribund shipping line, which is about to pass into outside control as a result of his neglect. But when Valerie, in a fit of anger, blurts out the truth about how their marriage came about, John loses all interest in Joan, returning to the company of his ex-girlfriend (Lillian Bond) and turning the matter over to his lawyers. Now Joan has to fight on two fronts, to help save her husband's business, and also to save their marriage before it's too late. Given this plot, it may seem odd that Double Harness was presented as a comedy, but it is, and a good one, too. The humor lies in the way the upper-class are shown "coping" with the Great Depression, and the witty presentation of the romantic flirtations in the lives of Joan, Valerie, and John (and their friends), as well as the tone of John and Joan's marriage -- Joan, in particular, has a wryly detached side that comes out even at her most unhappy moments. It's all very sophisticated, a comedy by adults, about adults, for adults, and it holds up amazingly well as a piece of entertainment across 75 years. In some ways, Double Harness is also a bit reminiscent of the 1930 version of Holiday, which is perhaps not entirely accidental or surprising, as the latter also starred Ann Harding, although Cromwell's 1933 film is a far more skillful and accomplished cinematic work by modern standards.
by Bruce Eder synopsis