After witnessing his best friend's murder, Gideon takes charge of Chicago's troubled 13th district, creating an app, allowing citizens to immediately alert the police.

Gideon and Murphy run into a pharmacy robbery, where he's inspired for new tech; Murphy hears someone could take down Giedon's plans.

A group of robbers kill a security guard who used the APB app before his death; Gideon redesigns a feedback chair, for use in the investigation room; Murphy learns that her ex-husband may be watching them.

Brandt's mission to catch criminals selling armor-piercing bullets goes awry; A task force led by Murphy's ex-husband threatens Gideon's future.

Gideon and Martinez want to employ a new technology to help their case after a man's extreme actions for justice are called into question; the assistant State Attorney continues his interrogation of getting about the 13th District.

After Gideon's father finds himself in trouble, he turns to Gideon for assistance. Meanwhile, Brandt and Goss work to track down the mastermind behind a huge grand theft auto case.

Gideon opens a nerdcon as the station goes back to basics. While at the nerdcon a threat is revealed on Gideon's life by a hacker who impressed Gideon. Brandt and Coss track a suicidal student , while secrets are revealed.

Gideon tracks down the culprit behind a series of terrorist attacks.