Danny considers retiring until Erin asks for his help with a case involving her ex-husband Jamie and Eddie pose as a couple Frank clashes with the new mayor.
A Mexican drug cartel targets Danny when he intercepts a shipment of several million dollars Jamie goes after a serial killer who preys on the elderly Mayor Poole confides in Frank that he plans to retire.
The team discovers a Russian spy ring hiding on Oahu when a Russian submarine appears off the coast.
Thieves kill a soldier and steal a shipment of high-tech small arms.
Several "widows" hire the HEAT to prove their common ex-husband is really dead.
Women around the world turn up missing in various vacation destinations and the H.E.A.T. is hired to find them.
Chief Boden makes a risky last minute decision to save his men Dawson continues to deal with her father Brett's childhood friend visits and strikes the attention of someone within the firehouse a fire at a high school hits close to home for Boden.
A warehouse blaze puts the fire and rescue squad at risk Dawson's father overstays his welcome at Dawson and Casey's home Casey fights for his first responders bill Mouch makes a serious decision Herrmann tries to make a young boy smile.
Mouch offers to help when an off-duty incident puts Cruz in a bad spot Casey takes on a powerful politician Lt. Severide makes life difficult for a new team member Dawson gets an unexpected visit from her father.
Fire and rescue are called when an old warehouse-turned-work space turns into a firestorm, trapping countless victims the doctors and nurses of Chicago Med deal with a barrage of patients as victims of the disaster are brought through the doors.
Citing a need for improvement, Chief Anderson reassigns members of 51 to other firehouses, leaving the crew members to make the best of their respective new situations Severide struggles with an important decision.
Chief Anderson feels his authority was undercut after Chief Boden makes a decision that overrides Anderson's when both squads respond to the scene of a dangerous accident Severide ponders a lifechanging decision Herrmann does a good deed.
A dangerous man is on the loose with a vendetta against Lt. Casey and the Firehouse 51 squad Antonio's ex-wife appears Casey has a gift for Dawson.
Dawson struggles to control her emotions during an ambulance ride with a pregnant teen the firefighters rush to a building fire Casey must make a quick decision when two victims both need life-saving assistance Severide shares a bond with Anna.
Severide agrees to a bone marrow donation Casey and Dawson attempt to find harmony at home Otis and Mouch plan to create a PSA to encourage people to join the Chicago Fire Department.
Dawson and Casey face legal issues as they try to retain legal guardianship of Louie Severide continues to look for a bone marrow procedure to help Anna Brett opens up to Dawson.
Following Hetty's sudden resignation, Callen and the team try to unravel the mystery behind her disappearance.
A man pretending to be a Navy SEAL is set on fire, leading NCIS to information about the location of a stolen item from a past case that could be used to make a bomb.
The entire city is looking for Ross's murderer, and Mike Hammer is stuck behind bars while the cops canvas the city, Hammer needs to post bail so he can track down the real killer and keep Lila safe.
The local jazz club features a talented singer who's captured Hammer's eye, but her taste in men puts her in danger with the death count on the rise, Hammer will go to any length to protect Lila.