Two sisters' bodies are discovered near the industrial town of Cannonbridge. As detectives Lambert and Kelsey investigate the double murder, they find themselves upsetting the locals. The girl in the green anorak who came into the pub one rainy evening was looking for her sister, who had left home four years before. Now, because an unexpected legacy could not be paid until both girls were accounted for, she is hot on the scent, never suspecting that for her it is a scent of death and that each step she takes to try to trace her sister Helen will soon be followed by Detective Chief Inspector Kelsey and Sergeant Lambert. It is apparent that the vital clue they are seeking lie in Helen's life between the time she left home and the November night when she had vanished without trace. Patiently Kelsey and Lambert follow Helen through various jobs, to the house where she had a flat, the clinic where she had an abortion, the young man from whom she bought a car. At no point could it be proved that Helen was dishonest, yet Kelsey suspects that the hard-working, helpful secretary knew more about her employers and their practices than some of them wished. And therein lies the clue to a double murder.