Plot Summary:Walter suddenly discovers a discrepancy in the amount of drugs in the lab. He questions Jesse, who claims to know nothing. Walter finds a fly in the lab, overturns equipment, and becomes determined to catch it. Jesse returns to the lab to find Walter has been there all night. Walter is extremely paranoid about the fly, vowing to catch it. Jesse tries to help but only makes things worse. Walter kicks Jesse out of the lab to catch the fly alone. Jesse turns off the lab's power and buys flypaper. Walter and Jesse continue to hunt the fly in the lab. Jesse puts a sleeping pill in Walter's coffee, unnoticed by Walter. Walter and Jesse discuss Walter's illness, and Jesse expresses happiness for Walter's recovery. Walter expresses suicidal thoughts, and Jesse comforts him. Walter recalls a conversation with Jane's father at a bar, explaining that his current persistence is for his family, which deeply moves Jesse. Jesse fulfills Walter's wish, catching the fly. Walter's sleeping pill takes effect, and he falls asleep. Jesse puts Walter in bed and covers him. Walter realizes Jesse has been taking drugs from the lab and warns him to stop. Jesse denies it, and Walter admits he is powerless over the situation. While sleeping at home, Walter hears the noise of a fly. He opens his eyes and realizes someone is watching him.