Dark Currents: The Code of Death

On a stormy night, an unidentified woman's body is found in the river, posed as if kneeling in prayer. There is a butterfly tattoo on her neck, sandalwood ash beneath her fingernails, and a hidden significance to the way her hands are folded. Detective Captain Chen Mo and forensic pathologist Lin Xia take over the investigation. While comparing DNA, they trigger an alert for an unsolved case from ten years ago. The victim back then had the same pose and a butterfly tattoo in the same place, and the killer had once sent letters soaked in sandalwood.

The graffiti of wandering artist Su Qing depicts details of the crime scene, but she is involved in a suspicious car accident. A sandalwood sample goes missing from Lin Xia's laboratory, and an insider's involvement begins to emerge. Another victim is found, with changes to the pose and tattoo. Su Qing appears at the scenes of both cases in surveillance footage, and her phone contains photos of the locations of future crimes.

As the investigation deepens, the clues point to philanthropist and businessman Zhou Zhengyang. A psychological profile suggests his motive for committing the crimes may be psychological compensation. A raid on his villa uncovers a hidden room filled with newspaper clippings about the cases and designs for the rituals. In a secret compartment, Lin Xia finds her father's work ID from ten years ago.

Su Qing's true identity is revealed: she is the sole survivor of the unsolved case from ten years ago, hypnotized and controlled by Zhou Zhengyang. It turns out that Zhou Zhengyang is obsessed with revenge because his first love died and his father was wrongly sentenced to death. In the end, Zhou Zhengyang takes Lin Xia hostage to complete his "final masterpiece." Chen Mo turns the tables by exploiting his traumatic memories, while Su Qing sets off the fire alarm system. The sandalwood ash reveals the truth. The case is solved, some find redemption and others a new beginning, yet sandalwood incense still drifts through the temple, as if hinting at something unknown...