Marco, Tato, Serena, and Leo are nine years old, and they are inseparable friends, ready to defend each other from their schoolmates’ bullying. On the evening of Marco's birthday, all four find themselves together to blow out the candles and unknowingly make the same wish: become adults. In one night's time, they find themselves magically the same age as their parents, but with the same behaviour and thoughts they have as kids..