Olivia popped in what seemed like the hundredth tape. Elliot sipped his coffee and thoughtfully watched the screen, "What day are we on?"

Olivia glanced at the paper under her arm, "Uh, last Tuesday."

The phone rang in her pocket. She pulled it opened and checked the caller Id. It said Warner so she immediately put it to her ear. "Benson."

"It was sodium barbital," Melinda answered, "Easy to find. It's a basic anesthesia."

"So Serena's going to be okay?" Olivia asked.

"She'll be fine," Melinda answered.

"Good," Olivia nodded, "Is that all you have for me?"

"Unfortunately," Melinda replied.

Olivia paused, "Alright. Thanks." Olivia set her phone down and looked at the screen again. "It was sodium barbital."

Elliot rewound the tape, "Look at that." He paused it and pointed to the janitor.

"What about him?" Olivia asked, "He's come in the same time every night."

"That's not a him," Elliot stated.

Olivia looked closer and saw a stray piece of long brown hair fall out from under the perp's hat. They both watched as the janitor walk past all the overflowing trashcans and dirty windows. She went straight to Alex's office, where she did exactly what they knew happened. She took a rag and coated the top of all of the drinks in Alex's refrigerator, then left.

"C'mon," Elliot told the TV, "Show us your face."

As if she heard him, the woman looked directly at a camera without realizing it and walked out.

"Oh my god," Olivia breathed, "That's Tracy Langan." Olivia grabbed her phone and quickly dialed Alex's number.

"Hello?" Alex asked.

Olivia was surprised by the way Alex answered the phone. She was expecting the same curt 'Cabot' Alex always answered the phone with. "Hey. We found out who it was. It's Tracy Langan, so if you see her call me immediately."

"Okay," Alex answered simply.

"Are you okay?" Olivia asked, "You sound…different."

"I'm fine," Alex replied, "Just at the hospital."

Olivia furrowed her eyebrows. Something about Alex's voice was tense. "Is Serena okay?"

"Yeah," Alex stated.

"Well…call me if you need anything," Olivia said.

"Liv," Alex paused, "I love you."

"I love you too," Olivia replied, "Are you sure you're okay?"

"Yeah," Alex said and hung up.

Olivia looked at her phone, "Something's going on with Alex."

"C'mon," Elliot stood up, "Let's go get Tracy Langan."

Alex closed her phone and set it on the bed tray, not taking her eyes off of the knife pointed at Casey's throat. Her eyes traveled up the hand that held it, up the arm, and to the face of Tracy Langan.

"What'd she say?" Tracy asked.

"They know it was you," Alex answered.

Tracy shifted her weight.

Alex looked at Casey's panicked eyes and then moved her eyes over to Serena, who was sitting on her bed with her legs crossed and her jaw set.

Olivia and Elliot had a hard time getting past the front desk at Langan's law firm, but when they did, they had to wait for him in his office.

"This place is huge," Elliot looked around.

"It's bigger than my living room," Olivia commented, standing behind a chair.

Langan walked in a few minutes later, "Detectives. To what do I owe the pleasure?"

"Where's your wife?" Elliot asked.

Lagan raised an eyebrow, "Why?"

"We have reason to believe she witnesses a homicide," Olivia added.

"She would have told me," Langan replied.

"We'd still like to talk to her," Elliot stated, "Where is she?"

"I haven't seen her today."

"Did she tell you where she was going?" Olivia asked.

Langan told Olivia and Elliot while setting his briefcase on his desk, "She said something about going to visit a friend."

"Where?" Olivia asked.

"A hospital?" Langan shrugged, "I don't remember. And the only reason I'm telling you is because I know she didn't see anything."

"A hospital?" Olivia's eyes widened. She nearly ran out the door with Elliot on her heels. She dialed Alex again on her way.

"Hello?" a woman's voice answered. It definitely wasn't Alex.

"Tracy?" Olivia asked.

"Hello detective," Tracy answered, "Alex has informed me that you've found me out."

Olivia motioned for Elliot to drive. She turned on the sirens and lights.

"I hear that you're on your way," Tracy added, "You better bring a body bag." Then the line went dead.

"Oh shit," Olivia looked at her phone, "Go faster Elliot. Tracy's at the hospital with Alex, Casey, and Serena."

"Do you really think a body bag is necessary?" Serena asked.

"You can take Alex's body out of here on a gurney if you'd like," Tracy smirked.

Alex looked out the window and saw a flashing light in the distance. It was a distinct flash that came with a police siren. She let out a long breath and hoped whoever it was would get there before Tracy fulfilled her threat.