A wealthy couple are killed; a series of copycat murders take place; and a boy may have been killed by an exorcist.
Rizzoli is reunited with an old high-school flame; a pregnant woman is murdered; and a woman dies during Fleet Week in Boston.
The duo's friendship suffers in the aftermath of Paddy Doyle's shooting; they put their differences aside to investigate the murder of a college student; and a strange encounter has unexpected consequences for Isles.
A state senator is assassinated at a community parade; Rizzoli investigates the death of a journalism student; and a body is found in a church.
Rizzoli tries to hide her pregnancy from her mother; a woman cannot remember who she murdered; and a serial killer uses online advertising to lure new victims.
In Season 6, Frankie shoots a man at a busy Boston underground station, and a murder victim is found buried in a shallow grave among the corpses at a university research facility.