Young and ambitious Captain Vivés has just been appointed group leader at the Grenoble Criminal Squad when Clara's murder case lands on his desk. Vivés and his team investigate Clara's complex life and relations, but what starts as a professional and methodical immersion into the victim's life soon turns into a haunting obsession.

When a team of explorers ventures into the catacombs that lie beneath the streets of Paris, they uncover the dark secret that lies within this city of the dead.