In the heart of Madrid's financial district, investigative journalist Elena Suárez stumbles upon a mystery that spans centuries. When a series of high-profile bankers commit suicide across Europe's major cities, she discovers a pattern that connects ancient musical frequencies with modern-day power.

Dark Prophet, an enigmatic music star, performs surprise concerts that leave audiences in trances. Ancient medallions appear at each death scene. And a message repeats: "The circle closes every 250 years."

As Elena delves deeper, she uncovers a secret society that predates the Illuminati—one that has used the mathematical patterns of music to shape human history since the dawn of civilization. With the help of Alexander Kane, a musician with his own hidden agenda, she races against time to prevent a global concert that could enslave millions through the power of forbidden frequencies.

From the historic streets of Madrid to London's modern skyline, from centuries-old libraries to high-tech concert venues, "Forbidden Frequencies" weaves together music, mathematics, and ancient mysteries into a heart-pounding thriller that challenges everything we know about the power of sound.

Some frequencies were meant to stay buried. Some symphonies should never be played.