When 6-year-old Lucy collapses at daycare, the team is mystified when, far too young, she starts developing symptoms of puberty. Tensions between Chase and Cameron lead House to intentionally assign them to the same tasks, including investigating the young girl's home.

Wilson prepares his 14-year-old leukemia patient, Nick, for a last-resort bone marrow transplant from his younger brother, Matty. With Nick's immune system completely wiped out from chemotherapy, Wilson is extremely cautious about keeping him healthy before the transplant. However, when Matty sneezes during a pre-op visit to his brother, Wilson knows that Matty is not healthy enough to donate.