House remains affected by memory loss due to a bus crash that has also severely injured Amber Volakis, Wilson's girlfriend.
Amber is being treated at Princeton General Hospital, where the attending physician says she is experiencing tachycardia that can't be explained as a result of the bus crash.
In the ambulance, Amber's tachycardia degenerates into v-fib; Wilson demands she be put into protective hypothermia in order to buy time for a proper diagnosis.
At Wilson's urging, House agrees to undergo deep brain stimulation to recover his memories of the evening of the bus crash and thereby help diagnose Amber.
[1] An acoustic version of Massive Attack's "Teardrop," the show's opening theme, can be heard in the middle of the episode in a short montage, by José González.