Lt. Benson (Mariska Hargitay) and her squad will face a code red situation unlike anything they have encountered before in the upcoming season premiere of "Law & Order: Special Victims Unit."

The official synopsis is out for the first episode of season 18 and fans are excited to see how the Special Victims Unit will handle such a dangerous new case.

The action will start when a kid is discovered abandoned in Central Park. As the authorities search for his parents, they will stumble upon an even bigger problem. Clues point to "a planned mass casualty event" in New York City. Benson's team must work alongside the joint-terrorism task force to locate the culprits and stop the carnage before all hell breaks loose.

As if the threat of many people dying is not enough to keep Benson busy, she will also be dragged into a messy situation with Assistant District Attorney Barba (Raúl Esparza). The lost kid's mother has been found, and she has something important to disclose to Benson. It looks like she will accuse someone, possibly the boy's father, of rape and torture. Benson and Barba, usually on the same side of the fence, will be divided in their quest to find out the truth.

Meanwhile, Hargitay recently tweeted her thanks to U.S. Vice President Joe Biden for being a guest star in the NBC series. It has been recently teased that he will appear in one of the upcoming episodes this September as a support to Hargitay's campaign against domestic violence. In her post, she praised Biden for his work as a fierce advocate of the said issue and his active role in spreading awareness to many people.

"The depth of [Biden's] integrity, commitment, and leadership has come to mean so much to me, to our community, and to survivors. There are no words for [his] commitment on these issues. I am so very fortunate to be able to call him my friend," Hargitay wrote.

"Law & Order: SVU" season 18 premieres on Wednesday, Sept. 21 at 9 p.m. EDT on NBC.