Lu is shocked to learn that she has a shaky professional history with Andy's replacement, Dr. Dylan West. After Lu is shot during a mugging, Dylan works to save her. The President's visit to Philadelphia impacts Rittenhouse when the Secret Service denies the staff access to the blood she needs.
Dylan's investigation into a patient's heart condition leads him to suspect drug use and eventually puts him face-to-face with a dangerous crowd. Lu discerns that a child is not being abused but rather has a medical condition that produces bruising.
Lu takes on the police after they Taser a child and it turns out the boy's aggression is triggered by a mercury-laden diet. One of Kayla's patients comes into contact with a deadly agent, causing the doctor to call Homeland Security. A woman with MS seeks out Dylan for help.
Lu learns that two children are infected with E Coli and need kidney transplants, but is soon surprised to learn the way in which they caught the bacteria.
Dylan tries to determine the cause of an outbreak of Legionnaire's Disease which reaches a well-known prep school, but only afflicts three people. Lu volunteers at a prison and finds herself in a battle with the corrupt prison system and an HMO who are pilfering funds used for medications.
The birth of a woman's twins reveals her adultery. Dylan tries to get a female high school kicker for the football team to realize the dangers of steroid use. Preparations begin for Lu's wedding to Jonas.
Dylan finds out that a summer fling from a decade and a half ago produced a daughter after the mother comes seeking his medical assistance. Lu tries to help a family come to terms when an accident leaves one of their own brain-dead. Jonas tries to find Lu's long-lost father and the gesture isn't lost on her.
Dylan tries to come to terms with his newfound fatherhood, especially in balancing his work and social life. Dylan's girlfriend falls prey to a lethal flu. Lu handles the case of an 11-year old with weight issues. Lu's wedding shower gets crazy.
Lu and Jonas' wedding day arrives. Dylan contends not only with a delicate in utero surgery on unborn twins, but also with his daughter being picked up by police for shoplifting. When he picks her up, a hostage situation develops.
Lu takes time away from her honeymoon to care for sick orphans in Costa Rica. Jonas helps out by getting them to Philadelphia for proper care. Unfortunately, the warm reception in the States doesn't happen when the FBI arrests Jonas. Nick returns with his sister and it turns out her pregnancy is actually a tumor.
Dylan tries to secure a transplant for a patient battling Down Syndrome but loses his case before the transplant committee. Lu tries to help gang members escape the lifestyle by faking their deaths. Lu reveals that she's pregnant.
Dylan takes on the governor as a patient and Lu tries to get the governor to reconsider the fate of a death row inmate. Kayla hopes Dylan can help her with a pianist who lost a hand. Peter takes it on himself to try and help teenagers be better fathers.
Lu handles the case of a patient who is faced with welfare fraud when a DNA test questions her as the mother of her children. Another stress to Lu's life comes in the form of news that her baby might not be completely healthy. Peter gets surprised by the results of some herbal remedies he attempts to heal his shoulder with.
Lu gets caught in the middle of a family's drama when one girl tells her that she doesn't want to donate a kidney to her older sister. Kayla and George vie for chief resident.
Dylan works to help a mastestomy patient stay in the hospital despite her insurance company mandating her release. A cerebral palsy patient legally goes after her mother for smoking while carrying her in the womb. Dylan teams up with Lu for a sex talk with his newfound daughter.
Lu works to save the lives of two different patients admitted to the burn unit. Kayla and Peter battle over how to handle a teen's death from heart failure.
Lu finds the hospital overrun during the holiday season even as she's short-staffed without Dylan. Lu reunites a grandmother with her three grandchildren after their drug addicted mother dies. Lana battles over the Christmas Spirit with the hospital Santa.
Kayla tries to befriend her long-estranged twin sister, Keisha. Keisha's actions lead them to believe she may be mentally ill. Dylan and Lu work to help a woman remain fertile after her appendix bursts. After Peter's dog bites a boy, the boy's mother has him sent to the pound. Peter looks into the situation and learns that the boy actually has a melanoma.
Lu tries to help a child suffering from a pulmonary condition through use of Viagra. Dylan tries to find cause in the Bible for a patient to fight after she believes her cervical cancer is punishment for infidelity.
Kayla lies to the girlfriend of a dead bank robber to keep her from detonating the bomb she says she's carrying. Peter searches the hospital for a missing boy. Lu fights to save a pregnant patient suffering from meningitis.
Dylan and Lu debate whether a patient should continue on a drug that has helped her condition, but has also caused brain lesions in laboratory mice. Dylan is challenged to hang on to Araya when her mother's parents arrive for her.
Lu goes into labor while trapped in a basement with Jonas, forcing Jonas to perform an emergency c-section procedure. A dying patient identifies her killer to Dylan, but when he comes forward with the information, Araya is endangered.