Dr. Catherine Black (Kelly Reilly) reveals to her therapist Dr. Helen Hartramph (Vanessa Redgrave) that she's feeling empowered, unstoppable and at the top of her game. This world-renowned neurologist has a secret that's becoming more and more difficult to control. In an event that occurred a week ago in San Francisco, she skips her meds hours before a big speech to the Neurological Institute of America. She lets room know they are all ignorant when it comes to the brain. The crowd goes wild with enthusiasm after her speech. Too bad this positive response was a hallucination.
Catherine becomes hyper-sexual later that night. She has sex in her hotel room with the stranger who was her driver for the evening. She doesn't even notice the guy swiping all of her cash. She's too busy jumping off the balcony and flying off into the night. Another hallucination. The episode she's experiencing is over by morning. In the present day, Dr. Hartramph asks if she wants to be exceptional and dead. Catherine gets the point. She takes her meds before heading off to work at a medical establishment known as the Cube.
Anthony is a young man who was supposed to be headed to M.I.T. in the fall. At the moment, he's manically painting the walls as Catherine speaks with his parents, who don't believe their son is schizophrenic. Anthony hears voices. Catherine tells him he shouldn't listen to them. He can trust her. Catherine believes his parents may be right. Perhaps Anthony doesn't have schizophrenia.
Will Van Renseller (David Ajala) wants to marry Catherine. The discussion about this is put on hold as they watch her niece, Esme (Siobhan Williams), compete in a basketball game. Catherine's brother, Joshua (David Chisum), is also there. Reagan (Laura Fraser), Esme's strict, health-conscious mom, is on snack duty. When the game ends, Catherine admits that she is bipolar to Will. She's fine when she takes her meds, but she has a tendency do very bad things when off them. Will realizes what she's saying. He orders her out of the car. This has Catherine recalling a past incident when another man left her upon finding out she was pregnant.
Catherine returns to the Cube as Anthony is having a violent episode. The boy sees fire in the room. Catherine shows him it's not really there. She convinces him to rest. Dr. Lina Lark (Ali Wong) says Anthony has a brain tumor. Dr. Owen Morley (Terry Kinney) introduces Catherine to Dr. Ian "Bick" Bickman (Ditch Davey), the new chief of neurosurgery. The confident doc vows he can get rid of the tumor. Moments later, Catherine finds Will waiting for her. He apologizes and she promises to stay on her meds. The two of them officially become engaged.
Catherine tells Esme the tale of how her mom killed herself due to their hereditary condition. Kids are likely not an option for that reason. She later catches Bickman having sex with someone. It has her thinking of her night of passion with the driver. She dumps all her meds down the toilet. The next day, she talks to Lucy, an elderly woman who is hallucinating about seeing a dwarf she calls Yojo. Meds help, but Lucy has nowhere to go. She has no family to help. Catherine realizes she's lonely. She misses Yojo. Catherine orders her meds to be stopped so Lucy can see her little friend once more.
Catherine is feeling the high of being off her meds. She does a sultry dance in the stairwell. She catches Bickman popping pills to help him focus on his upcoming surgery. The two of them are turned on. Moments later they are undressing each other. A short time after that, Catherine gets sexually aggressive with Will. She tosses her engagement ring at him and flees to the streets. Joshua is able to track her down. Catherine is sedated during the ambulance ride to the hospital.
Once she stabilizes, Catherine meets with Dr. Hartramph. Even though so many things went wrong, she still has the one thing that truly matters: her daughter. Catherine stops by to see Esme. Reagan won't allow it. Catherine may have been the one who gave birth to Esme, but Reagan says that she is her mother. A phone call is made to Dr. Hartramph. Catherine wants a reason to go on living. She gets one. Her work is waiting for her.
Anthony is back to his old self after his surgery. He thanks Catherine for understanding him when no one else could. As for Lucy, she's much happier now that Yojo is back in her life. And Will is back in Catherine's life. He liked what she did to him that night she went wild. He wants to do it again.