A story that takes place after the events of Disney Pixar's Luca, Cinque Anni starts after our main protagonist, Luca, graduated from Upper Secondary School. From the moment he steps off of the train and enters into Portorosso once more, Alberto, his one special person, is there to meet him. What Alberto doesn't know is that Luca is hiding a big secret, something that could change both of their lives forever.

It's the fifth Summer Alberto gets to spend with Luca and Giulia. However, this one is unlike any other. Atom bomb threats are all over the news in Italy. Luca and Alberto are scared that their life on the surface will come to an end . As for Giulia, along with all the other humans she's worried her life will come to an end. But, Alberto's determined to keep his promise to Luca; "Can you promise me you'd spend your last moments with me if it were all to end?"