"16+" centers on a group of four friends – Māra, Mārtiņš, Edgars, and Pauls, who study in the same class. As the new school year begins, two girls – Laura and Amanda – join the class, whose arrival and attitude shake up the seemingly stable friendship. A series of events begins, in which everyone is drawn into it, and no one will get out of it easily.
Edgars leaves Māra. Next week, the school inauguration event is being prepared, for which Māra is responsible. Paul is supposed to give a speech, but at the most important moment, Paul has disappeared.
Māra's incoherent speech is interrupted by Amanda and Laura's show. Māra is shocked. Later, on a class evening, Māra is quite drunk and responds to Amanda's provocations with her trainer's whip, hitting her in the cheek. Laura has filmed the whole thing. Edgars takes Laura home, but Māra wanders alone along the tracks at night and sends Edgar desperate messages. The next morning, Amanda meets Laura and prepares plans for revenge against Māra and her company.
Māra meets with her friends, and everyone realizes what trouble is looming because of the video Laura made. Amanda demands money from everyone and an interesting performance from the guys so that the company can atone for its guilt. Pauls wants to help Māra, but Edgars and Mārtiņš resist. Māra's mother, Gita, starts a conversation with Māra, but Māra is too absorbed in her own problems and doesn't understand anything her mother says.
Māra names Paul and persuades him to make an important announcement during a sex education lecture. Mārtiņš meets Paul at school, the two almost fight, and Paul tries to run away from him. Māra does not expect Paul during the lecture and tries to give the speech herself. Māra has an argument with her mother. A man tries to get to know Māra in the stairwell, and she perceives it as sexual harassment.
Paul returns to school after an accident. Edgar's birthday is approaching, and Laura has also been invited to the celebration. Māra is not thrilled about it. Amanda's friend Gatis gives Laura a valuable gift and gives both girls a dangerous task. Mārtiņš buys grass from Gatis. When Māra arrives at Edgar's birthday party, she does not feel welcome there. Laura and Amanda try to complete Gatis' task, but they are interrupted and seen. Amanda acts inappropriately in a stressful situation.
No details
Gatis and Amanda threaten Mārtiņš. Gatis attacks Amanda. Mārtiņš, Pauls and Edgars meet and each has their problems. Māra wakes up after a big party and meets Anna. Māra cannot remember the events of the previous night.
Laura and Amanda argue about the computer. Amanda posts part of the video from the dedication night. Paul defends Māra. Anna talks about the night Māra spent with Garo. The neighborhood children come to Anna's place. Laura meets with Mārtiņš to find out the truth about what happened together.
Laura meets Amanda and Gati. Pauls meets Māra's desperate mother. Mārtiņš tries to persuade Edgar to listen to Laura. Paul tries to persuade his friends to help look for Māra. Laura comes to Edgars, but Edgars doesn't want to talk to her. Anna is having another party.
Edgars meets Mārtiņš, and their conflict only deepens. Māra meets Paula, who is offended and jealous. Laura records Amanda's story about what Gatis is doing. Amanda runs away from Gatis. Laura talks Amanda into staying with Mārtiņš.
Mara reconciles with her mother. Laura offers to help Mara. Gati is arrested. A party is organized.