A narcocorrido music video, produced by a Mexican band, depicts the rise of a mysterious figure known as "Heisenberg" — the alias Walt uses in the drug trade — celebrating his blue meth and warning that he killed Tuco Salamanca. The video circulates on the internet and reaches the DEA, where Hank and Gomez watch it with a mixture of amusement and concern. The song confirms to the DEA that Heisenberg is a real and growing figure in the regional drug trade, not merely a street rumor. Hank adds the Heisenberg case to his active investigations. Jesse expands his distribution network, emboldened by his new fearsome reputation after the Spooge incident. Combo, Skinny Pete, and Badger each work separate corners, and product is moving steadily. Jesse manages the operation with increasing confidence, collecting money and distributing fresh batches on a regular schedule. Walt continues chemotherapy and suffers debilitating side effects — hair loss, vomiting, and fatigue — but insists on continuing to cook. He and Jesse produce another large batch in the RV. Skyler's suspicion deepens after the confusing phone call with Gretchen. Skyler contacts Gretchen directly and the two meet for lunch. Gretchen, unaware of Walt's lie, is bewildered by Skyler's gratitude for supposed financial support. Skyler realizes that Walt has been lying about who is paying for his treatment, but she does not yet know the truth about where the money originates. She confronts Walt indirectly, asking pointed questions about the Schwartzes, and Walt deflects with anger, accusing Skyler of going behind his back. The argument escalates, and Walt storms out. Walt drives to Gretchen's home and confronts her, furious that she spoke with Skyler. Gretchen is hurt and confused, reminding Walt that she and Elliott genuinely offered to help. Walt tells Gretchen that his personal life is none of her business and severs the relationship. Jesse's operation faces a new threat: two rival dealers on the south side, working for an unidentified distributor, begin encroaching on Combo's territory. Combo reports the incursion to Jesse, who tells him to hold his ground. The territorial tension escalates quietly, setting up a confrontation that Jesse does not yet fully appreciate.