House is surprised when his ex-girlfriend, Stacy Warner, makes a visit. He's even more surprised when he finds out that she's not there to see him, but to get help for her ailing husband. As House debates over whether or not to take the case, Cuddy decides to make him a substitute lecturer to a class of medical students. While there, he weaves together three stories of patients who all have the same symptom. The lecture is one that the students, and all those who hear it, will never forget.