An absurd law prevents John, an unrecognized child at birth, from knowing the identity of his biological parents before his 100th birthday. To succeed in attracting public opinion, his only hope is to obtain the complicity of Gustavo, the only unrecognized-at-birth centenarian alive. The only one who would have the right to avail himself of this legislation but seems to have no interest in doing so. The Most Beautiful Century of My Life tells of the meeting between a centenarian projected into the future and a young man anchored in the past and of their unexpected friendship.

In a wonderful hotel on the seashore, preparations are underway for the wedding of Eleonora who will get married in the afternoon to Fabrizio, known as El Tigre. Each of the excited bridesmaids – Vanessa, Linda and Akiko (pregnant with Billo) – gives the bride an accessory to make her outfit more chic. Instead Polina, her mother, gives her a box of jewels: “they belonged to your poor father. The only thing we have left of him." Eleonora is stunned to see that inside her there is not a jewel as she expected but three teeth, a 'relic' of her father who was killed years earlier in an attack. And since then Polina has asked her to fulfill her father's wish to be buried in Gorizia, in a small cemetery on the border between Italy and Slovenia.

Tangled up with blackmail and crooked cops, the son of a former gangster seeks out his father's old friends, who risk everything to save him.