Noah Selvaggio is a retired chemistry professor and widower living on the Upper West Side, but born in the South of France. He is days away from his first visit back to Nice since he was a child, bringing with him a handful of puzzling photos he's discovered from his mother's wartime years. But he receives a call from social services: Noah is the closest available relative of an 11-year-old great-nephew he's never met, who urgently needs someone to look after him. Out of a feeling of obligation, Noah agrees to take Michael along on his trip. Both come to grasp the risks people in all eras have run for their loved ones, and find they are more akin than they knew.