Who Says It's Fair (1) (S04E16)

In this two-part episode, Mary Beth finds a lump in her breast but is reluctant to discuss it or seek help. Chris learns of her situation when Harvey, worried for Mary Beth, sneaks off to inform her. After some persuasion, Chris manages to get Mary Beth to visit a doctor and seek a second opinion. Meanwhile, the detectives are on the hunt for a missing child. Cagney suspects the boy ran away due to his mother's inadequacies, while the mother feels the search effort is biased against her because of their race. Eventually, the child is discovered in an underground tunnel, prompting Chris to go in after him. As Mary Beth prepares for her surgery, Chris is unable to be by her side due to the sergeant’s exam, but she rushes back just in time to hear that the operation was a success.