Mickael and Yann haven't spoken to each other since the tragedy that broke up their family 18 years ago: a terrible incident that led to the death of their father and 15 workers in a mine that's been closed ever since. Mickael believes the methane explosion that killed them was an accident; Yann thinks it was plotted and then covered up by a powerful industrial family, owners of a local methane company. Now, the two brothers, one a uniformed cop, the other a detective, must work together to solve a murder at the same site of the explosion so many years ago. They'll soon discover the two events might be linked. Their investigation will bring to light the shadowy history of the region, as they unearth grudges and emotions from the past that many would prefer remained buried.