The Low Tone Club centers around Amaranto Molina, a music teacher in a school where only those who meet the financial requirements are promoted to other levels. Every year, the school director chooses five students (called the High Tones) from the rest to join the precious school band for teens.
Molina, the music teacher, is left in charge of the unselected students, embarking on a heartwarming and energy-filled musical journey thanks to the teacher's unmatchable skills.
Besides teaching, Molina inspires his students to do better, despite not being selected. Eventually, Molina's students learn about the teacher's puzzling past, which he strives to conceal.