Zero?

When intern doctor Lin Xia rescues a mysterious man covered in blood and holding a silver gun in a midnight convenience store, her peaceful life is completely shattered. His code name is "Zero", and the key he carries is related to a deadly biological experiment. In order to avoid the ubiquitous "shadow" pursuit, people from the two worlds were forced to flee side by side. With the muzzle in the dark and the approaching crisis, is she his only salvation, or is she the next target to be devoured?