A serial rapist sends a letter to the squad announcing his return to Philadelphia after five years and his plan to strike again.
Finch and Reese meet their match: a tech billionaire whose curiosity and endless resources could expose their identities and ruin their efforts to save his life.
Efforts to find an 8-year-old boy kidnapped for ransom are hindered by tension between the child's estranged parents; Sgt. Benson is asked to take the lieutenant's exam and officially become the leader of the squad.
In an emergency courtroom set up in a hospital, Alicia and Will battle an insurance company that refuses to pay for life-saving in-utero surgery. Meanwhile, Alicia gives Peter a proper welcome home.
When the son and housekeeper of a pair of prominent biologists are murdered, detectives suspect the couple's work on a controversial pharmaceutical study may have made them targets for the killer.