When a rampaging Dr. Cox suddenly shows up at his door in a strange funk, J.D. sees a possibility of a breakthrough in their relationship -- until he learns that Cox loses control in almost an annual rite. Meanwhile, Turk elects to partner with Elliot on a research project so that he can maneuver her back with his buddy J.D., and Carla struggles to fulfill a comatose patient's final request -- playing heavy metal music in his room.