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.