Danielle Mitchell is suffocated by an assailant in her apartment. The autopsy reveals a cork in her throat. The detectives find out she had a secret boyfriend and later discover it is Paul Westourt, the prosecutor in Plymouth County. Paul successfully prosecuted the Cork Killer weeks earlier.
Paul and Danielle were having an affair but Paul swears he never entered her apartment. Later, his DNA is found there and he is arrested.
Out on bail, Paul's wife fears he is suicidal. Jane and Maura find him on a bridge. Just as Jane convinces him that she thinks he's innocent, he slips and falls. Jane jumps into the river after him.
Angela gives Maura advice on meeting Jack's 12-year-old daughter but the pre-teen turns out to be more like Maura than she expected.