Alicia investigates a judge's motive after he overturns a straightforward plea deal she negotiated; Diane receives an offer she cannot refuse, much to Will's satisfaction.

The staff of Gaffney Chicago Medical Centre's new ER are given a baptism of fire when the department's opening is interrupted by a train crash.

With election day approaching, the three mayoral candidates make last-minute appeals. Carcetti wrangles for votes as he responds to a potentially devastating smear, and Norris and Greggs get a lead on the Braddock case.

Bubbles identifies a witness for Herc. Colvin offers an incentive. Andre seeks help from Proposition Joe.

Burrell sends out a mandate, Kevin comes clean to Marlo, Bubbles gets revenge, and Chris takes care of a problem.

Beck and Stabler investigate a car accident involving two foster children, which leads them to the foster parents and some dubious medical practises involving controversial attachment therapy.

On the trail of missing bodies, Freamon turns to a higher authority after being rebuked by Landsman, and Carcetti finds his erstwhile promises of prosperity undermined by the school debt.

As McNulty and the detail continue to stake out Marlo's crew, newly-elected Mayor Carcetti is finding he is stuck between keeping his promises on education and his promises on law and order.

Elena confronts her ex-husband about his behaviour.

Marlo tries hard to win the favour of the Greeks.

Baltimore's renewed police commitment brings fresh recruits to Daniels; Carcetti is forced to make a dangerous political deal; Haynes approaches Templeton about his sources.

Carcetti maps out a damage-control scenario, McNulty asks Landsman to pull police off the homeless case, Haynes' concerns about Templeton fall on deaf ears, and Dukie seeks out an old mentor for a loan.

Carcetti's chief of staff orders Rawls to initiate creative remedies for the rising crime rate, Freamon's vigilance provides a lead and sends the department into overdrive, and Michael is suspicious about his latest assignment.

Dr Choi treats a teenage mother who abandoned her newborn baby in an alley. The nurses surprise Dr Manning with a baby shower.

Dr Connor Rhodes must deal with his past when he takes care of a family friend; Dr Halstead struggles with a surgery that could impact a young musician's hearing.

A mass shooting at a cinema inundates the hospital with gunshot victims, including the shooter. Dr Rhodes faces a crisis of conscience.

Rhodes and Zanetti race to save a member of Firehouse 51, April's brother struggles during his first day at the hospital, and a woman saved from a burning building leads to a bigger mystery.

Manning faces a challenging case involving a teenager after her return from maternity leave, while Dr Choi is determined to help a naval worker whose serious issues are downplayed when visiting royalty becomes the focus of concern for medical staff.

Sharon struggles with legal issues concerning an urgent transplant recipient, while Dr Manning faces problems at home.

Dr Halstead resuscitates a patient with stage four cancer despite the family's objections. Meanwhile, the nurses work on improving patient satisfaction.