Underage tells the story of how the Serrano sisters, namely Celine, Carrie, and Chynna are forced to face adulthood too soon by going through various emotional mishaps with their family, after a malicious video involving the three of them went viral online.
Reese is a con artist from Manila who dreams of living like royalty. An opportunity arrives in the form of Princess Ulap, a runaway princess from the mysterious kingdom of Oro, who looks exactly like her. Switching places in exchange for gold, Reese flies to Ulap's kingdom where she meets Caleb, a young and determined reporter who is doing a documentary on the island of Oro. The road to happily ever after becomes bumpy when the man in search for truth begins to fall in love with the fake princess.
Lando, a laid-back fisherman, enjoys joining the yearly "Aguman Sanduk" fellowship cross-dressing festivity with his peers of Alpha males as an enjoyable rest and recreation. Meanwhile, his mundane everyday life back in his isolated hut surrounded by fish pond waters is beset with a horrifying secret about him being physically abused by his wife, beating him to a pulp and sometimes degrades him verbally with no remorse constantly about women being linked to him. Lori, the wife, is set to leave for abroad as a domestic helper. She harbors ill feelings against Lando whom she caught meeting with his ex-girlfriend in a rendezvous. Her unusual violent streak becomes acceptably normal to Lando, who easily yields to his guilt. In a heated, passionate moment of desire, Lori steps back upon realizing that she doesn't love Lando anymore.
The mother, Carmen, is a woman of three kids who was abused and abandoned by her husband. But she learns how to move on as a grade school teacher who puts up her own business and succeeds as an empowered woman.