The Sarno River is a waterway that springs in the Picentini Mountains and extends to the Gulf of Naples. Its length is only 25 km but its reservoir, which is not easily extended, reaches 500 square kilometres and involves almost one million people.

Although in the past, being easily navigable, it allowed cities like Scafati and Pompeii to flourish for a long time, to the point of also being described as a deity, today the river represents, according to a parliamentary act of 2005 and the Handbook of Water Purity, the most polluted perennial watercourse in Europe and among the five most polluted in the world.

This condition of extreme pollution is mainly due to the chemical substances illegally poured into the Solofrana River, the largest tributary of the Sarno, by the hundreds of tanning industries that rise above the watercourse. Among the most dangerous substances there is Hexavalent Chromium, a chemical used for the colouring of hides which, when poured in large quantities, colours the water with a reddish tone. This substance is present inside the river water with values 900 times higher than the norm, together with other carcinogenic substances including pesticides used by the numerous farms within its water basin.

These substances are partly transported to the sea, where the currents repel them towards the coast making more than 7 km of beach between the Gulf of Naples and the Amalfi Coast impassable. Another large part, instead, is deposited on the river bed, to then cement and raise its level up to several meters. This factor, together with the enormous quantity of solid waste thrown into the different channels that accumulate in various points of the river and do not allow the normal passage of water, causes the river and its rivers to overflow on rainy days, causing serious flooding of contaminated water that invades the cities and crops along its course.

Within this framework, Metàstasis explores the delicate and controversial symbiosis between the river and the people living along its banks. In a climate of total abandonment and isolation from the outside world, the people, victims and perpetrators of this condition, live their relationship with the river every day: some of them have decided to fight this insurmountable and now irreversible disease through environmental activism, information and public awareness; others continue to take advantage, consciously or unconsciously, of the serious lack of control and sensitivity to the issue, perpetrating the destruction of this important ecosystem.