Hanna Stein, a photographer living in East Berlin, sees the world through synesthesia, where sound transforms into color. When she discovers old tapes left by her dissident father, documenting the voices of political prisoners, Hanna risks everything to cross the Berlin Wall and restore the damaged recordings. Her journey leads her to Viktor Hahn, a scientist obsessed with preserving sound through light. Together, they embark on a perilous mission to save the voices of those silenced by the regime, even as the Stasi closes in on Hanna's every move.