On the latest episode of "The Mentalist," the CBI team investigated the death of five D.E.A agents in Corpus Christi, Texas.

In "White Lines," it's revealed that the agents were shot in their office, and the office's security cameras had been destroyed in the shooting as well.

After hearing the D.E.A's suspicions, it leads the team to a Corpus Christi narcotics organization. They believe the agents were murdered in retaliation after the D.E.A killed one of the organization's members during a drug bust. The organization is called Gulf Coast Ring, and it controls the drug flow in Corpus Christi.

Jane (Simon Baker) becomes interested in investigating the girlfriend of Richie Vargas, who is the ring member who was killed by the D.E.A. Her name is Krystal Markham, who is played by guest star Brianna Brown.

Yet, Lisbon (Robin Tunney) and Cho (Tim Kang) discover that the murderers are not a part of the Gulf Coast Ring.

Fisher (Emily Swallow) and Jane find Krystal, but she says she doesn't know anything about the slayings of the D.E.A agents. Then, to the surprise of Fisher, Jane asks Krystal out on a date.

Lisbon, Cho and Fisher then find the dead bodies of the men who killed the D.E.A agents.

While on the date, Jane convinces Krystal to reveal information to the FBI. She says she knows where the condo is of one of the suspects, who is named Paco Perez. Yet, she says she's scared that Perez will have her killed once he learns she's been speaking to the FBI.

Cho, Lisbon and Fisher then go to Perez's condo, but he has already left.

Jane then drives Krystal home. Once Jane leaves, Krystal goes inside to find Paco Perez waiting for her. It's revealed that Krystal is the mastermind behind the organization, and is the person responsible for the murders.

Krystal kills Perez, and makes it look as if he was killed during a shooting with the police.

Later, Jane asks Krystal out again, and she agrees to meet with him.

Lisbon and Fisher then find out that Krystal had been in the D.E.A office once, when she was interviewed about her boyfriend. Lisbon is suspicious when she sees Krystal looking at the mirror in the video surveillance, which has a hidden camera behind it. 

Lisbon figures out that Krystal is the head of the ring, and is the one who tipped off the killers to the existence of the cameras. Lisbon tries to warn Jane, but it's too late: he's already on a second date with Krystal.

Krystal brings Jane onto her friend's boat. Jane reveals to Krystal that he guessed since the beginning that she was hiding something. She is about to kill him when the FBI arrives and puts her under arrest.

On the next episode, "The Golden Hammer," Jane and the CBI team will investigate the murder of a man who was trying to convey important information at the time of his death--information that most likely led to his murder. 

The synopsis reads, "Jane and the FBI investigate the murder of a high-tech cartographer who may have unearthed a spy ring before his death."

Check out the promo for "The Golden Hammer," which airs Sunday, Jan. 12 at 10 p.m. on CBS.