Voight and Lindsay are called in to investigate a decapitated body. 

Roman and Burgess are called by Andrew's mom. Her ex got drunk and beat her. 

They find out the victim was a stripper and Ruzek and Olinsky go to the club to ask questions. They find fake IDs in her locker. 

Voight gets a lead. Halstead, Ruzek, and Dawson follow up and they arrest the guy, but Ruzek is injured. 

They question him about the victim, Victoria, and a mob organization called The Outfit. His lawyer arrives and he confesses to killing her. Lindsay thinks the lawyer is involved with the mob and convinced him to confess. 

Lindsay and Halstead search the boat he supposedly killed her on and find no trace evidence. 

They question Victoria's sister and discover that she was also dating the suspect. She was with Charlie, the suspect, the night Victoria was murdered. 

They find out that Victoria was pregnant and ask Charlie who she was seeing. He tells them it was the mob boss, Carlo.

Roman and Burgess are looking for Andrew's dad, Rtichie. They track him down and Roman tells him to stay away from Callie. 

Voight goes to talk to Carlo. Carlo says he got a vasectomy and can't be the father. 

Mouse finds hotel footage that showed the attorney with Victoria. They bring him in, but Voight lets him go, which angers Lindsay. 

Roman and Burgess arrive at Callie's to find her injured. Roman goes after Ritchie and shoots him. He swears he had a gun, but he was unarmed.