Jerry and Tom are two grandparents who compete for the sympathy of their grandchildren.
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.
While he is speaking on the phone with a member of his staff, Filippo has a severe headache and faints. As soon as he regains consciousness, he calls his friend Pippo for help and asks him to invite the group of old friends to join, too. Little by little the four friends remind him of happy moments shared in the past and Filippo gradually manages to remember with their help….But something unhappy comes back to their mind….