During the traditional carnival celebrations, the dead body of a young girl is found near the small town of Bellinzona, in Southern Switzerland. The officers engaged in the case find themselves investigating crimes rooted in a past full of shadows.
In the spring of 1873, people from all over the world come to the tiny village of Göschenen in the canton of Uri, to work on the biggest and most spectacular construction site of modern times: the tunnel through the Gotthard.