Parents of little Noah, who is suffering from a genetic disorder, a Swiss couple decides to conceive a child, but a very specific one. Conceived in vitro, the new baby should be compatible genetically with their sick son. And so, with the help of a genetic magic wand, little Elodie was born.

A year later, she gives some of her blood and bone marrow to her immunodeficient older brother. So at last, thanks to his little sister, Noah can get out of his sterile chamber.