What French-language film was Billy Wilder's directorial debut?

Billy Wilder’s French-language directorial debut was Mauvaise Graine.

Released in 1934, the film is a French action comedy about Henri Pasquier, a wealthy young man who becomes involved with a gang of car thieves after his father cuts off his support. Danielle Darrieux stars as Jeannette, while Pierre Mingand plays Henri.

Wilder made the film in Paris after leaving Berlin in 1933 amid the growing threat of Nazism. The production used real streets and improvised locations, including a converted automobile shop for interiors. Its energetic car chases and partly silent, jazz-inflected style show Wilder experimenting before his Hollywood career fully began.

The wording can hide a small crediting nuance: Alexander Esway is also credited as co-director. Nevertheless, Mauvaise Graine is conventionally identified as Wilder’s directorial debut. It was his last European film; he next directed the American comedy The Major and the Minor in 1942.