Depressed by his loneliness, Paul-André, a shy and wealthy man, offers to rent the family of a good-natured woman with two kids in exchange of settling his debts.

Two sisters, their families, and sometimes complicated lives.

Sarah is a French astronaut training at the European Space Agency in Cologne. She is the only woman in the arduous program. She lives alone with Stella, her seven year old daughter. Sarah feels guilty that she cannot spend more time with her child. Her love is overpowering, unsettling. When Sarah is chosen to join the crew of a year-long space mission called Proxima, it creates chaos in the mother-daughter relationship.