At the start of World War II, 14-year-old Carrie and her younger brother Nick are separated from their mother and evacuated from war-torn London to a rural village in Wales, where they now live with a puritanical shopkeeper and his spinster sister.

Detective Chief Jane Tennison has been transferred to a new station and now has the job of cleaning up the streets of Soho. The team goes into the underworld of teenage prostitution, pornography and runaways.