Black Box

Dr. Bickman rushes his doorman to The Cube after he sees him collapse from a buried aneurysm. With a second bleed imminent, he makes a choice to perform an alternative procedure to repair it. After revealing a difficult diagnosis to a young mother, Catherine finds herself sinking into a deep sadness. In her desperation, she misleads a nurse into supplying her with oxycodone. Catherine turns to her brother for help, though he begins to wonder if he's become an enabler. Catherine reveals to Will that their relationship is over.

Catherine is experiencing hallucinations and refuses Dr. Hartramph's urging to be admitted into a hospital. Her behavior is becoming increasingly manic and it isn't long before Mahmoud begins to piece together what she's seeing. Meanwhile, Bickman is reluctant to go back into the operating room after Joey's botched surgery. Catherine encourages Bickman to see Lina so that she can re-wire his brain. A woman confronts a knife-wielding man on the street and the team wonders if it's really a display of bravery or if she has an absence of fear.

After undergoing treatment in rehab, Catherine returns to face the fallout at home and at The Cube. While trying to get her life back on track, Esme's biological father arrives and is in desperate need of a transplant. Catherine is faced with the difficult decision of having to reveal the truth to Esme about who her real parents are. Owen is agreeable to having Catherine back at work, though it isn't without strict parameters, making it a challenge for Catherine to earn her credibility back.