When Della, a seemingly healthy and active 14-year-old, suddenly collapses during a skateboarding exhibition, House and his team struggle to diagnose her condition and reassure her parents who already have to cope with their son's terminal illness. After her body rejects a donor lung, and with time running out to save her life, Della's family is left with little hope of securing a new donor and faced with a seemingly impossible decision regarding the fate of both children. Meanwhile, House tries to appease an elderly father and his son at the clinic, and House and Cuddy begin to face the challenges of taking their romantic relationship into the workplace.