Trace inspection expert Lu Chenzhou was transferred to the grassroots level due to the sacrifice of his partner, and formed a partnership with Gu Yunshu, the captain of the criminal investigation detachment. The two led technician Zhou Xiaoman, and with the assistance of a foreign aid team (cremation engineer Song Laogui, online ride-hailing driver Atang, and pet undertaker Su Wanqing), they successively solved ten seemingly unrelated and difficult cases.
But as the investigation deepened, Lu Chenzhou discovered that each case left a "superfluous trace": fingerprints that did not belong to the scene, hidden GPS coordinates, and trace elements that should not be present. These traces all point to a person who should have died three years ago - his best friend in the police academy.
Protagonist group:
Lu Chenzhou (male protagonist, 35 years old): Trace examination expert, lonely and paranoid, with a mysophobia about physical evidence, nicknamed "Lu Ruler"
Gu Yunshu (female protagonist, 29 years old): Captain of the criminal investigation detachment, resolute and action-oriented
Zhou Xiaoman (technician, 26 years old): rookie mark inspector, diligent but irritable, the "eyes" of readers
Foreign aid group:
Song Laogui (60 years old): Cremation industry, good at skeletal analysis and reverse physical evidence
Atang (28 years old): online ride-hailing driver, retired scout, living map
Su Wanqing (32 years old): pet mortician, chemistry enthusiast, microscopic evidence expert
