Léna, 28 years old, community manager, has just joined the communications department of the Paris Police Prefecture, which is seeking to modernize its image. At the same time, a serial killer is rampant in the capital. Commissioner Agathe Ruffin is in charge of the investigation. The killer uses social networks to destabilize the police, thus attracting Léna's attention. Intoxicated by adrenaline, she then embarks on a dangerous game by agreeing to communicate with him.