After her colleague DCI John Shefford has a heart attack, DCI Jane Tennison is given the opportunity to do what few women have done with the Metropolitan Police: lead a major murder investigation. Her superiors aren't too keen to appoint her and the welcome she gets from the murder squad is chilly to say the least. Her main nemesis is DS Bill Otley, an old-timer who was close to Shefford and doesn't think a woman should heading a murder investigation. The prime suspect in the case is George Marlow who admits to having slept with the victim, Karen Howard, on the day she died. He's known as something of a ladies man and and a traveling salesman who regularly frequented prostitutes. As Tennison delves deeper into the case, she finds an number of unsolved cases that match not only Marlow's sales route, but coincide with his business trips to the areas in question. With the growing support of her team, she works herself into exhaustion, affecting her personal relationships with her live-in companion, Peter Rawlins, as well as her extended family.