David and Davide, raising their seven-year-old daughter Lucia, spend a September day by the lakeside. In this season of transition, with the shifting weather echoing the moods of the water, what begins as an apparently peaceful moment of everyday family life slowly unravels under the weight of the couple's unspoken tensions. Left to herself, Lucia turns a simple corkscrew into a B-2 stealth bomber, takes flight, and disappears.