The film opens in Paris on the eve of the presidential elections, just after a huge terrorist attack at the Gare Austerlitz. The government accuses Islamists. But a computer hacker who considers himself an anonymous law-upholder carefully studies images of the explosion and tracks down, from a distance, the trio responsible for the crime, in particular a young couple. Using the city’s surveillance cameras, he spies on and manipulates them. In the process, he realises that the truth can have many faces.