After witnessing the murder of Elliot Sully, his CFO and friend, genius billionaire Gideon Reeves of Reeves Industries makes a proposal and deal with the mayor to get the troubled Chicago Police 13th District and upgrades it with his company's latest technology, notably by creating the APB app that allows citizens to immediately alert the police to a crime, bulletproof cars and improved weaponry. With the aid of patrol cop Officer Theresa Murphy, Reeves also sets out to bring justice to his friend by finding his killer.

Newly promoted Murphy gets her first case as a detective with Gideon on a ride-along. They run into a pharmacy robbery and a young girl gets seriously injured while they were attempting to chase down the robber. Gideon modifies the police force's motorcycles to go faster in order to outpace and capture the thief, who happens to be a race car driver by profession. Later, Detective Murphy finds out that her ex-husband, Scott, is head of the mayor's task force to take down Gideon's plans for the 13th District.

The 13th District responds to a call from Murphy's friend, Linc, a retired cop turned security guard who used the APB app before he was killed by five jewelry thieves armed with AR-15s. When they capture one suspect who doesn't give up any information, Gideon redesigns a chair that uses biometric feedback sensors to measure stress levels and tests it in the interrogation room. The jewelry store robbery is discovered to be the first step in a robbery of an armored truck full of money. This is later averted when the bomb that the robbers were carrying detonated thanks to a hacker friend of Ada's doing her a favor, unbeknownst to Gideon and the police force.

When Brandt goes undercover to collar an illegal weapons dealer (Tim Griffin) who has been supplying armor-piercing bullets to the drug dealing community, a problem arises with how to get a wire into the meeting. Gideon proposes they use a material embedded with extremely fine wiring to fabricate a jacket, thus making the entire jacket a transmitter, though not without some restrictions. Meanwhile, Murphy's ex-husband Scott interviews Officer Reyes, who was shot during one of Gideon's first days running the 13th, in an attempt to take down Gideon's plans for 13th.

A fellow MIT grad goes to great lengths to get a meeting with Gideon, hoping that he and the officers of the 13th can take down the people dealing a dangerous new synthetic drug that has harmed his daughter. Things get complicated when the man tries to take the law into his own hands. Meanwhile, Scott ramps up his investigation into the sketchy procedures used by Gideon and the 13th.

Gideon's con man father Joe (John Heard) gets in trouble with a mobster and turns to his son for help in exchange for aiding the 13th precinct in their takedown of the crime family. Meanwhile, Brandt and Goss try to collar a highly successful teenage auto thief.

Gideon is the keynote speaker at the Windy City Tech Summit, where he is joined by Lauren (Kim Raver), the CEO of Reeves Industries. While Lauren is concerned that the 13th Precinct is just another one of Gideon's expensive "hobbies", evidence surfaces that Gideon may be the target of a murderer who has already killed once to gain an all-access pass to the summit. Meanwhile, Brandt and Goss deal with a suicidal young man, both divulging secrets in order to save him.

Lauren presents Gideon with the idea of "APB Prime," a security system they can sell to the broader public, an idea that Lauren wanted Gideon to introduce during the shareholders meeting later on. Meanwhile, Gideon and Murphy attempts to solve a series of unusual arsons that appear to be related to gang wars that turn out to be something completely different, while Gideon struggles with what to say for the shareholders meeting to keep his company profitability.

When an FBI informant working within a drug cartel is feared to be dead on a boat sunk in Lake Michigan, Gideon retrieves a $50 million submersible he developed for NASA to explore the wreckage. The dead body aboard turns out to be a cartel member, so now the team must work to keep their informant safe from the wrath of the cartel leader. Gideon struggles with keeping the ownership of his company as the board of directors threatens to vote him out due to his recent extravagant spending on the 13th Precinct and disregard to the company affairs. Meanwhile, Danny Ragabi (Ty Olwin), a hacker from Ada's past now known as DV8, wants to disrupt the work of the 13th Precinct, as he believes Gideon is creating a police state.

A serial rapist attacks Captain Conrad's old neighborhood and the drug dealer now running the neighborhood wants to dole out his own brand of justice. With the neighborhood community not cooperating with the police, Conrad, Murphy, and Gideon are stuck with collaborating with the drug dealer to find ways they can work together to expose and collar the rapist. Elsewhere, Ada works against the clock to protect herself and the 13th from DV8's schemes.

Despite Ada's previous threats, DV8 takes on Gideon and the 13th, with the intention to expose Gideon's secrets. Fearing for Gideon's safety, Conrad sends him home with Murphy. While the 13th is dealing with DV8's terrorist bombings throughout the Precinct, Murphy and Gideon are ambushed by another set of DV8's men, forcing them to retreat into Gideon's secret lab which is hiding a secret project.

Making use of the opportunity, the mayor blames Gideon for the recent terrorist attacks and threatens to disband the 13th. Meanwhile, DV8 reveals himself and prompts the 13th to find him. While the 13th attempts to locate DV8, DV8 continues to use his technological skills to disrupt the city. After DV8's assassination attempt on Gideon fails, Gideon and Murphy learn that DV8 has targeted city hall and race the clock in an attempt to save the mayor's life.