Curtis questions Ethan's interest in the investigation of the mysterious death of a beautiful twin; Megan runs into resistance while investigating the death of a patient at the hospital where she used to work.

Megan suspects foul play when a young philanthropic socialite dies; the investigation is interrupted by Kate's personal life.

When a young nanny is run down by a car and killed, the 5-year-old child she was watching is kidnapped; an interrogation goes awry.

After Peter rescues a woman from a house fire, Megan discovers another person in the house who died. Peter takes the discovery personally since he had no idea anyone else was in the house. A veteran arson investigator challenges Megan at each step in her investigation. When Megan complains to Kate the response she gets only intensifies the tension between the two women.

A champion equestrian is killed and potential drug use is suspected, but when Megan's daughter, who also rides, overhears details of the case, she leads the team to a clue and possibly the murderer.

When a popular 17-year-old high school student is found dead after a rave, the team must decipher various unknown drugs in his system and multiple bruises to figure out the cause of death. Meanwhile, Meghan is finally starting to date again after the divorce, but her ex-husband springs some shocking news on her and her daughter, causing tension at home.