The unknown Halstead

She what?

"Detective, She works for us"

"I'm sorry, she what?" Adam blurts out.

"She is a special agent for the FBI, part of a new undercover operation" Agent Green responds coolly.

"Oh so she's undercover? And she looks way younger than she is, so this is an agent abduction not a kidnapping?" Burgess replies.

"Well, no. She just turned fifteen." Green states "Like I said she is part of a new operation, the criminals are getting younger, so why shouldn't the agents?"

"That's insane" Hailey begins "You need years of training to work for the FBI. How long has she been working with you guys?"

The agent scans the room before sighing and saying, "If you're going to help get our agent back, I guess you'll need to know more about her than you currently do. Give me an hour to see what I can tell you and then I'll brief you all on this girl."

After an hour of waiting the agent walks back into to bullpen, and slaps the girls government photo onto the board, claiming the attention of everyone in the room. "Alright this is Elizabeth, she goes by El, Ellie, Eliza, Beth, and dozens of other code names. She is 15 and part of a task force of young agents across the country. She was one of the original agents in this program since she has been training with us since she was 7. She was placed into Chicago about five years ago, to work on cases, however you may not recognize her since she changes her appearance quite often. For example as of a few months ago, she now has blue streaks in her hair. She is highly trained in martial arts and combat, similar to what your man Halstead was trained in for the Rangers." 

Jay is about to question this statement when his phone begins to go off. Everyone looks at him as he answers it. "Hello?"

"Check your computer Jay"

"What? Why?"

"You may find a very interesting piece of footage on there."

"What do you-" The person hangs up and Jay opens a link on his computer, "um guys, you might want to check this out." Everyone gathers around to see Elizabeth on the screen covered in cuts and bruises with her hands behind her back.

An unknown figure walks forward and grabs the girls face shaking her awake, "Wake up, you have an audience. Hello Jay, Voight, and the rest of intelligence I have your friend here."

Everyone turns to each other, he never addressed agent Green. So why is he referring to her as their friend?

"Did you really think you could send in this little junior detective to spy on me? You don't think I know a Halstead when I see one? And before you say how'd you know? I know people, yeah, I ran a DNA test, you think you can send me Jay Halstead's sister and get away with it?" The girl slowly raises her head and looks at the man, "I don't have a brother." 

"Lies!" he responds "So why don't you tell me what you know about that man Halstead before I deal with him myself!" "Leave my dad alone he didn't do anything!" El cried. "Oh no, honey I'm not talking  about your dad, he died a few years ago. What? Did your brother, the great Jay Halstead refuse to tell you that?" Then El looked at the man, anger in her eyes,"I already told you, I don't have a brother."  The man then stepped on the girls cut in her stomach causing her to scream out, she then began to pass out  from pain as she whispered, "Will, Will, I need bandages." As the man straightened up he spoke with a smile on his face, "you're absolutely right young one, I forgot about the other Halstead, Will. You!" he pointed at someone off camera "Bring me Dr Halstead, now!"

The screen then went dark. Everyone slowly turned to Jay who was still trying to process the information, when he realized what the man said, "Atwater, Ruzek go to med, get Will and bring him here. I'll call ahead to let him know you're coming. And you," he points at Green, "You have some serious explaining to do."