This audiobook is narrated by an AI Voice. When relentless rain tears open the hillside beneath Heidelberg Castle, something older than myth breaks free.

A chamber of black granite. A silver–lead seal shattered.

And a song no human mind was built to survive.

Journalist Lukas Bergmann is the first to hear it. A whisper behind the forehead. A promise of peace. A call to fall.

As bodies begin dropping from the castle terrace with serene smiles, Lukas realizes he is already marked.

Two unorthodox priests arrive in the storm, dragging with them secrets buried for nine centuries and weapons that look more like relics than salvation. Together they must ascend the soaked mountain, seal the chamber, and silence three ancient sirens before their combined voices turn Heidelberg into a mass grave.

But the song is inside Lukas now. And the closer they get to the source, the harder it becomes to tell where the melody ends and his own thoughts begin.

In the dark above the Neckar, something sings.

And it is hungry.