While trying to figure out the disease of a man whose tongue has swollen grossly, an old patient of Dr. House comes back to seek revenge on the doctor due to the pain he caused his family. House wakes up a patient of his medical team, with one odd anomaly: his leg no longer hurts. After other scientifically improbable and horrific accidents throughout the day, House discovers that what's going on around him isn't real, that he's hallucinating.