Jane and Maura are asked to present the case of a serial killer at a symposium for law enforcement; Jane and Maura make a discovery.
The squad investigates when an amateur drag race turns deadly; Jane turns to Lt. Martinez for help and he seems to be thwarting her investigation.
The squad tries to solve a homicide case that is muddied by conflicting evidence; Maura must decide if she is going to take in her recently paroled grandfather; Jane and Casey must decide between their careers and their relationship.
A kidnapper dressed as a clown re-emerges after 20 years; Jane's relationship with Casey grows more serious; Maura inadvertently gets in the middle of another relationship.
A musician is stabbed in a bar; the squad realizes that the stabbing victim had something to hide; Jane's father returns with shocking news.
When a food truck chef dies suddenly, all signs point to poisoning; Tommy announces some big plans; Maura's birth mother tries to make amends with her daughter.
A senator's daughter is found murdered; Tommy begins to slip back into old habits; Jane reveals some shocking news.