-Isabella Valdez is strangled in a church and stuffed inside a baptismal font. Her body is found at TJ's christening.
-Isabella was four weeks pregnant and marked with a gang tattoo. Several girls held her down, fractured her arms and forcibly inked her.
-Her boyfriend, Samuel told his father Mateo who said he would help. Instead Mateo, a former gang member himself, killed Isabella because he believed the gang would kill his son if he tried to take her away. Samuel hung himself when he realized what had happened and ended up in critical condition.
-Tommy forgets to file the custody papers for TJ. Lydia becomes engaged to Stuart who wants to move them to Texas. The Rizzolis are distraught until Lydia finds out that Stuart is allergic to animals, and she's always wanted lots of dogs.
-Frankie becomes a floating detective due to budget cuts. The same cuts may force the detectives in homicide back into uniforms.