Sergeant Tong is wracked with guilt after he unwittingly kills a young girl whilst capuring a criminal named Cheung. When the girl's sister is later kidnapped in a ploy to get Cheung released, Sergeant Tong vows to find and rescue her before she comes to harm.
In a world split by a gravity wall where time moves differently, a woman from the Aurora Zone and a man from the Evergreen Zone fall in love, despite the impossible challenge that one day for her equals one year for him.
