Frank deals with a whistleblower, who claims to have evidence of abuse throughout the NYPD Danny and Baez investigate a woman who was hit by a car.
Erin and Anthony try to keep a prominent community activist, who isn't a citizen, from being deported Frank must determine if the NYPD should participate in the U.S. Marshals' high-profile raid of a local gang.
A beautiful lawyer distracts Tommy from investigating a car bombing that killed an island president.
A mafia don goes to Puerto Vallarta to surrender himself for a reward to give his daughter as a wedding present.
Things don't go as planned when Dawson and Antonio's parents come to town for their anniversary Chief Boden deals with his stepson James' secret Casey tries to save a young boy during a call to a warehouse Otis and Kidd become competitive.
Dawson faces repercussions after she hits a pedestrian with the ambulance en route to a call Casey and Severide continue to investigate an arson case Chief Boden must decide whether to attend an important event in New York.
Casey is unable to save a woman trapped in a burning house Herrmann is determined to catch a mysterious tagger that targets the firehouse Boden has an unexpected visitor a teenager is injured during a romantic proposal.
Casey is forced to use extreme measures to save a father and daughter from an acid spill Dawson and Brett respond to an elderly woman who has a difficult senior advocate Otis shares some exciting news.
Casey gets help from Susan Weller for an urgent personal matter Severide is given an opportunity to travel with Travis Brenner Stella saves a street kid from a tunnel fire.
Detective Holloway testifies in court as part of an undercover operation, leaving Severide to watch her young son a fire at an art gallery with a victim trapped inside leads Cruz to make a rash decision.
Casey attempts to use political influence to remedy a gang retribution incident Severide helps Holloway in a dangerous undercover investigation.
A call takes a bad turn when Brett witnesses a murder while aiding a victim who has a leg wound a restaurant fire has people trapped inside a vault Mouch gets cold feet about his upcoming wedding.
Severide is led to reexamine a case from the past while he investigates the discovery of a baby's body in a chimney with election day nearing, Casey prepares for another confrontation with Alderman.
A propaganda attack causes Casey to reconsider his run for alderman when a man is trapped inside a burning car, it seems the fire may have been set intentionally Trudy's nerdy brother plans Mouch's bachelor party a kidnapping investigation.
Firehouse 51 responds to an unusual call from another firehouse the addition of a new firefighter (Miranda Rae Mayo) has repercussions Casey realizes that certain voters have personal agendas for wanting him elected.
In order to protect his best friend and main informant, Deeks resumes a former alias that he dislikes.
Hammer goes to Texas to attend a wedding, but when the bride goes missing, he must find her before a ring of organ thieves steals her heart.
Hammer is the prime suspect in the murder of a radio psychologist who advised her listeners to leave their lovers.
Lindsay goes undercover in hopes of finding a police officer who targets women leaving a local casino Burgess needs Platt's approval to move forward with her plan Antonio offers to take Roman's place in an upcoming boxing match.
Voight wants to make his former cellmate a confidential informant as the unit tries to take down a big cocaine supplier and local dealers Burgess makes a decision about her relationship with Ruzek Roman works with Firehouse 51 to fund a wedding.