Casey and Severide find themselves at odds after Casey argues with him over the best way to save a teenager entangled in barbed wire. When Casey looks to Boden for help smoothing out the situation, he comes to the realization that he will have to fix it himself. Elsewhere, Otis tries to convince Casey to participate in the beta test for an expensive piece of new firefighting equipment imported from Japan. Meanwhile, Kidd and Hope come to blows over a payroll issue and Brett goes on a date with a doctor she meets during an ambo call.
In a flashback to Iraq in 2007, the events leading up to Megan’s kidnapping are revealed. In present day, Owen and Megan hash out old wounds.
Brian heads to a trendy, exclusive new bar near Munty docks. He proves a hit with the bar's cool clientele, but are they what they seem? Barbara bumps into an old school-friend who offers her a rare magic object.
Katie tries to impress her friends by going to a hip Halloween party with Portia; Chuck is asked to use a new smart screen on the show but tries to get out of it by convincing Carol that it is possessed.
While Liv is busy running the free world, the team at QPA works with an unexpected client to solve an important case. At the White House, Mellie prepares for the upcoming Nuclear Summit with President Rashad and Prime Minister Nazari.
Sarah previews this year’s political Halloween costumes and sends friend Tig Notaro to get auctioneer lessons. Senator Al Franken is her guest.
Noel treats a Labrador suffering with severe arthritis in its elbow, and suggests using stem cells to help with the inflammation, while one of the team's senior neurologists deals with a Chihuahua born with fluid on the brain. Plus, a man comes all the way from France with his Labrador cross, which requires high-end surgery for elbow dysplasia.
In Mobile, when a quick money scam ends in a double murder, a rookie homicide detective takes it personally.
Jack looks to interrogate Frank, while Anna tries to escape Little Big Bear. Elizabeth finds a key witness, but Gagnon exploits her weakness.
When Red provides exclusive intel on an international terrorist, it puts Liz and the Task Force on a collision course with a rival unit from the CIA. Meanwhile, Red and Hawkins lay the groundwork for their new business venture, and Tom goes undercover in search of information.
When Intelligence busts a meth lab run by gang leader Marshall Carter, they uncover a re-homing scam in which children adopted from foreign countries are abandoned, then sold online. Meanwhile, Atwater struggles with the difficult decision about whether to move his siblings Jordan and Vinessa to a safer environment outside of Chicago.
Phil and Claire still want to celebrate Halloween in a big way, but it seems no one shares their same enthusiasm making them wonder if maybe everyone is right. Over at the Pritchett’s, Mitch and Cam are frustrated by how long Jay is taking to finish their kitchen remodel, which forces Mitch to finally stand up to his dad. Meanwhile, Gloria’s hospitality is wearing thin when Cam oversteps his boundaries as a house guest.
Archie gets frustrated by the lack of progress made in catching his father’s shooter, so he takes matters into his own hands to send the gunman a message. Meanwhile, Veronica is thrilled when Hiram’s attempt to start fresh means she gets to introduce him to her friends, including Archie. Elsewhere, Jughead starts his first day at Southside High and is befriended by a Southside Serpent named Toni, while Kevin’s attempt at having a little fun causes Betty to grow concerned for his safety.
The DiMeo kids mistakenly eat old Halloween candy that causes feverish dreams of horror and wish fulfillment, and Kenneth agonizes over which era of Michael Jackson to dress as for Halloween.
Mike and Ant try to arouse the passion of the Saab enthusiast community by restoring a rusty, non-driving 1973 Saab 96 to its past glory. Will their restoration pass muster with one of the car world's most passionate fan bases?
Morgan lends emotional support to Garcia when she experiences anxiety over a case that is personal to her from her past.
Dan's quit his job as a teacher and is applying his unique work ethic to a new profession. With Aunt Nesta and his mum in a retirement village, Dan is on a hunt to find his soon-to-be family a home.
Westport is known for its Halloween tradition of leaving an anonymous note and goodies on a neighbor’s doorstep (called a “Boo”). Katie tries to play it cool but is absolutely giddy when the Ottos receive their first “Boo.”