As it turns out, Maddie is staying with the Thibaut family, who are working for the French Resistance even as their son, Etienne, is working for the Nazis at the Ormaie Gestapo.
Because Etienne's family is local, they're required to serve the Gestapo staff a home-cooked meal once a month. We assume while seriously covering up any Resistance activities.
This month, Etienne shows up for Sunday dinner wearing a serious goose-egg. When his family gives him a hard time about it, the woman who comes with them, who we can only assume is Fräulein Engel, tells Mitraillette, the eldest Thibaut daughter, that he got the injury from a woman.
It's been three weeks since their arrival in France, and Maddie still doesn't know where Julie is, but she's pretty sure Julie is responsible for Etienne's injury.