The father of 27-year-old engineer Léo, a farmer, took his own life three years ago. Now, the brilliant and fun-loving engineer from Berlin has to return to his hometown of Doubs to sell the farmland to a company drilling for rare metals. However, the strange behavior of the local trout makes him suspect that the drilling is polluting the river of his childhood. While investigating, Léo is forced to confront his grief along the way.