A bipolar neuroscientist humanely deals with a manic teen who has a brain tumor and a woman with dementia. Her boyfriend proposes but, struggling with her desire to live life to the fullest, she sabotages things by tossing out her meds.

A brain surgeon kills his patient when he has a seizure during surgery; a young girl hallucinates that her head explodes; Dr Black tries to help but are lies in her way? Her boyfriend confronts her for the truth.

Dr. Black treats patients with Capgras delusion and a woman whose brain only sees half a picture. In retaliation for her one night stands, Cat's boyfriend confesses cheating on her and a confrontation ensues between his mistress and Cat.

Ali discovers that Leo, Dr. Bickman's rival, doesn't have super-memory but is faking it due to a brain tumor. A new patient turns violent. Dr Black loses her ring before her engagement party.

Dr Black treats Jacob, a rich Jewish man with God delusions; Arthur relapses so Dr Black gives him hallucinogenic mushrooms. Dr. Lark, who refuses to leave the office, gets an ultimatum from her date.

Ian and Catherine work to remove a bullet from a Pulitzer Prize-winning journalist without help from modern technology. Meanwhile, a high-profile makeup artist suffers a minor stroke leaving him color blind; and Catherine meets Will's parents.

The Cube is under attack by a violent gunman hounded by voices; Dr Bickman must operate on his shooter. Dr Black treats a patient with alien-hand syndrome and Will suspects she is lying when she cancels their date.

Trying to help a sax player with hand tremors who fears brain surgery, Dr Black introduces him to her musician father. Leo begs Ian for a letter of recommendation and Catherine declares her feelings for him.

Dr Black refuses to give up on a girl dying of rabies. She goes manic while searching for a cure and returns Will his engagement ring, this after he'd told her he'd finally fired his mistress Delilah.

A doorman collapses, so Dr. Bickman rushes him to the cube and performs an alternative procedure. Meanwhile Catherine gets depressed after making a tough diagnosis. Joshua fears he's enabling his sister.

Catherine returns to work after a month in treatment but can she keep her job? Esme's biological father needs his daughter's help and Esme finds out about the adoption.