As the kidnappers make their demands clear, the Intelligence Unit race to find Antonio's son by any means necessary.
As the Intelligence Unit attempt to prevent a dangerous new weapon reaching the streets, a house search results in a traumatic incident for Ruzek.
Halstead is suspected of wrongdoing when a bystander is shot during a sting. Voight seeks out Antonio Dawson and asks him to return to Intelligence full time.
When a woman ends up dead at a Maroon 5 concert, Mac and the team find themselves in danger. When they discover that the cause of death is linked to several victims over several months, they face a rush to save one of their own.
When a Navy SEAL is charged with murdering her superior, Madeline must prove her innocence; Levi presses harder for insight on Rosemary's life in high school; Bellows takes a drastic step in re-examining her murder.