Jane and Maura investigate the death of a young woman who is found washed up on the beach. Maura confirms that she drowned and manages to trace the exact location by analyzing the water in her lungs: a tank in an old fish factory. Jane is somewhat upset to find that an old flame, police Lt. Rafael Martinez, is back in Boston. They had worked together in the narcotics division but their relationship ended after a confidential informant had been killed and Martinez left to join a special task force some 8 years ago. The dead girl is identified as Brenda Thompson, a journalism student who was pursuing a drug story on her college campus. When Jane finds Lt. Martinez's business card among her possessions, it seems that he was using her to get information. Meanwhile, Maura learns that she may be in danger owing to her father's activities.

The hit-and-run murder of a high school science and driver's education teacher focuses on a group of friends who were also students of the victim.

The squad gets involved in an incredibly dangerous scenario when a horrifying incident occurs during a drag race; Jane gets a lead that points to drug trafficking being the motivation for a murder; an investigation is hindered.

A security guard in a weed store, stops a robbery. The guard is shot and wounded as he kills one of the thieves. The police have lots of questions that go unanswered. Rizzoli & Isles search for the dead robbers accomplice. Later Rizzoli continues her efforts to protect Isles and Angela.