L'Homme du Niger plot
In French Sudan, three friends who are soldiers, each in their own way, live according to their colonial ideal. There is Bourdet, a physician, founder of an Institute of Studies on Leprosy. In addition, there is the commander Bréval, whose dream is to provide Sudan with irrigation using dams and locks that are being built on the river Niger. And finally, there's Lieutenant Parent, the younger of the trio. François Mourier, a historian and former minister, comes with his daughter Danielle to visit the leprosy clinic and then chose the place to build the first dam. Parent falls in love with Danielle, but Bréval loves her too.