Season 1
Following the collapse of their school, three working-class friends, Samuel, Nadia, and Christian, are awarded scholarships at Las Encinas, Spain's most prestigious private school. The scholarships are funded by the building corporation that was responsible for the school's destruction. The three are originally rejected by wealthier kids at Las Encinas. As the school year continues, their lives become increasingly entangled in a clash of lifestyles, resentments, and envy, The spectator is told stories of the characters' relationships that lead to Marina's murder through a succession of flash-forward scenes of police interrogations.
Season 2
The second season follows the events leading up to Samuel's disappearance after the murder is revealed. Meanwhile, Cateyana, Rebeka, and Valerio, three new kids, arrive to the school, each with their own dark secrets. They make friends with the pupils in their class, while Samuel works on clearing his brother's name "Nano" after being accused of Marina's murder. Meanwhile, Polo attempts suicide to clear his conscience, but with the help of Cayetana, learns to live happily ever after. Because of the pressure of preserving Polo's secret, Ander's mental health deteriorates. Carla is duped into believing Samuel is dead, so she confesses to Polo's crime. Polo is incarcerated, but two weeks later is released and returns to school.
Season 3
At Las Encinas, the students are in their final semester. During their graduation party, the students are interviewed about Polo's death in a flash-forward scenario. With the exception of Valerio, Polo and Cayetana are shunned by their classmates. Samuel and Guzman continue their plan to bring Polo's misdeeds to justice. Lu and Nadia are competing for a scholarship to Columbia University, which leads to a fight between the two. Ander is diagnosed with leukemia and begins chemotherapy, creating friction with his family. Lu unintentionally stabs Polo on the night of their graduation, and Polo slips and falls to his death. Samuel, Guzmán, Ander, Omar, Nadia, Carla, Valerio, Rebeka, and Cayetana all agree to keep the murder a secret. Polo's death is considered suicide after the police are unable to uncover a suspect, and his parents tell the authorities that he confessed to Marina's murder. Samuel, Guzman, Ander, and Rebeka return two months later to complete their last year alongside Omar, who has now enrolled as a full-time student.
Here is a short trailer of the show:
https://www.youtube.com/watch?v=QNwhAdrdwp0&t=11s