Pratt and Neela rush to the hospital to help out in the aftermath of a shoot-out in the emergency room. Sam finds herself on a terrifying ride with her unstable ex-husband and his violent cohorts.
As Abby and Luka cope with their newborn baby's life-and-death struggle, they are shocked to receive a surprise visitor: Abby's mother Maggie. Sam returns to Chicago and Gates makes a risky decision.
Neela is hauled over the coals by the new surgical chief. Pratt copes with a flood of new interns. Gates is assigned to assess the condition of an older man who comes in with congestive heart failure.
Pratt finds juggling the interns and residents a challenge. Neela continues to be the target of her supervisor, who assigns her demeaning tasks. Gates copes with his complicated living situation.
Kovac attempts to recall his treatment of stroke patient Curtis Ames as he prepares for his day in court. Returning to work after her maternity leave, Abby worries that she has lost her skills.
Kovac anxiously awaits the decision of a jury in the negligence case pitting him against Curtis Ames. Neela tries to prove to Crenshaw that she's ready for surgery. Morris is upstaged by Weaver.
During a trip to the park with her child, Abby inadvertently meets Curtis Ames. Gates and Neela argue with each other at a hospital board meeting. Morris and Sam try to treat a belligerent patient.
After a group of confused, homeless kids enters the emergency room, Gates, Abby and Neela must quickly determine one child's ailment before it's too late. Abby and Kovac argue about a diagnosis.
At Thanksgiving, Abby is forced to respond when a bus crashes down the side of a ravine. Neela accepts an invitation from Gates to visit his house after work. Pratt discusses his brother with Weaver.
Pratt struggles to come to terms with the discovery about his brother's sexual orientation. Kovac spots Ames outside his apartment but chooses not to tell Abby. Gates begs Neela to give him a chance.
Ames issues a restraining order against Kovac. A homeless boy convinces Gates and Ray to help his friend, who is in critical condition. Dubenko gives Neela the chance to be part of a holiday miracle.
When a patient dies after being prescribed the wrong medication, Pratt and medical student Hope wonder if they're responsible. Kovac is forced to make budget cuts that could affect one of the doctors.
Kovac gets jealous when Abby gives too much attention to a patient. Meg pulls a deadly stunt when Gates moves out of their shared apartment. Weaver makes a decision that will change the ER for ever.
Gates and Neela try to revive Meg after they find her unconscious in her car. Sam suspects she may know who set fire to her home. Tensions mount as Ames gets more and more desperate to seek revenge.
Abby and Sam treat an obnoxious aspiring comedian with mysterious symptoms. Pratt is questioned about the death of a patient. Neela is thrilled when Dubenko lets her assist with kidney donor surgery.
When a woman comes into the ER with acute liver failure, Gates and Kovac face a moral dilemma. Neela also ponders right and wrong. Ray investigates the accidental fall of a squad of cheerleaders.
Abby and Pratt work speedily to save a family suffering from frostbite after getting stuck in the snow. Neela is jealous when Dubenko brings in a new surgical intern. Gates's father Mike reappears.
Sam and Morris are caught off-guard when a woman comes into the ER taking photos alongside a terminally ill patient. Neela feels upstaged by Dubenko's new favourite. Sam pines for her absent son.
When a young man comes into the ER with heart failure, Kovac and Gates must deal with his helpless father. A man risks his life to be a Good Samaritan. Pratt attempts to make amends with his brother.
Kovac is under pressure to deal with an overflow of cases before the ER shuts down for renovations. Sam befriends terminally ill photojournalist Diana. Tension between Gates and his father boils over.
The ER staff are surprised when they arrive for the department dinner and find out that one couple are about to tie the knot. Meanwhile, Ray can't seem to handle seeing Neela and Gates together.
Kovac and Abby get used to their new roles as husband and wife, while Hope and Morris enjoy the honeymoon suite. Pratt attempts to win somebody over. New physician Dr Kevin Moretti means business.
Dr Moretti is ready to make major changes. Kovac puts his honeymoon on hold to be with his ailing father. Gates is called home when Sarah panics that she might be taken away. Neela's life is in peril.