In the wake of Gus Portokalos and Ian's father Rodney's passing a year ago, the Portokalos family is grappling with grief. Nick, now separated, returns home, displaying immature behavior. Athena and her husband Yiannis are caring for Maria, who is battling dementia. Toula and Ian, though happily married, are facing the challenges of parenthood as their daughter Paris struggles with the responsibility of college, this is completely unbeknownst to them.

Victory, a distant relative and the mayor of Gus' hometown Vrisi, invites the family here for a supposed reunion. On the flight, Aunt Voula introduces her assistant Aristotle, Paris' college-mate, and Toula reveals she's bringing Gus' journal, containing his life story, to give to his three childhood friends in Greece as promised.

They arrive in Athens, where Victory greets them, and go sightseeing. In the nearly abandoned Vrisi, they find Gus' childhood home and meet Alexandra, Gus's old flame. There, Victory confesses there's no reunion, hoping the Portokaloses would revive the village.