Cardia Beckford lives with her father Isaac, but her life is marked by fear as people see her as a monster due to a deadly substance in her body. Her father embedded the Horologium, an eternally beating heart, in her chest, which can produce infinite power, but also causes her skin to destroy anything it touches. The British military takes Cardia into custody in an attempt to harness the Horologium's power. She's then rescued by Arsène Lupin, a gentleman thief, who joins her on a journey to uncover the truth about Isaac's connections to the terrorist organization Twilight, Cardia's missing memories, and the mysterious Horologium.