After the new season started off with a bang last week, Wednesday's Episode 2 of "Criminal Minds" will give fans another thrilling investigation, as the team works to foil a gas attack in L.A. in "The Witness."

In the Season 11 premiere, viewers were introduced to Aisha Tyler's Dr. Tara Lewis, a forensic psychologist who has become the newest member of the Behavioral Analysis Unit (BAU) team.

A preview clip of Wednesday's episode suggests that Tara will also play a significant role in helping the BAU find the suspect responsible for a poison gas attack on a Los Angeles bus that kills at least 10 people.

"Death within minutes," Spencer (Matthew Gubler) says in the video teaser.

Fans can also expect to see a variety of guest stars this season, including "The Mentalist" star Tim Kang and Marisol Nichols of "Teen Wolf," who will both be featured in the next episode. A synopsis of Episode 2 reveals that Nichols will play a FBI agent who helps the BAU to prevent another devastating attack in L.A. Meanwhile, Kang will play a medical supply worker.

According to CarterMatt, the synopsis reads as follows:

"When a Los Angeles bus is attacked with sarin gas, the BAU must act quickly to find the suspect before a larger-scale incident occurs, on 'Criminal Minds,' Wednesday, Oct. 7 (9 p.m., ET) on the CBS Television Network. Guest stars include Marisol Nichols (NCIS, "24") as FBI Agent Natalie Colfax, who assists the BAU with the investigation, and Tim Kang ("The Mentalist") as Charlie Senerak, a medical supply worker."

CBS also released a photo from Wednesday's episode, showing Nichols in character as FBI Agent Colfax speaking with Tara and Derek Morgan (Shemar Moore).

Season 11 Episode 2 of "Criminal Minds," "The Witness," will premiere on Wednesday, Oct. 7 at 9 p.m. EDT on CBS.

Watch a preview below.