Walt uses his chemistry knowledge to synthesize mercury fulminate — a crystalline explosive that looks similar to methamphetamine. He packs a small amount into a bag and drives to Tuco Salamanca's headquarters alone. Tuco's armed guards let Walt inside, amused by the mild-looking older man. Walt introduces himself as Heisenberg, a name he invents on the spot, and demands payment for the meth Tuco stole from Jesse plus an agreement to buy future batches at a fair price. Tuco laughs and threatens him. Walt picks up a crystal from the bag and hurls it at the floor, triggering an explosion that blows out the windows and sends Tuco and his men to the ground. In the stunned silence, Walt calmly repeats his terms. Tuco, shaken but impressed by Walt's audacity, agrees to pay for the stolen meth and to purchase the next batch — fifty thousand dollars for two pounds of product. Walt walks out with a bag of cash. He returns home buzzing with adrenaline and has aggressive, spontaneous sex with Skyler, who is startled by his sudden intensity. Meanwhile, Hank's investigation into the blue meth progresses. The DEA identifies the chemical signature of the product as extremely pure, and Hank presents findings to his team suggesting the cook is likely someone with advanced chemistry training, not a typical cartel chemist. The investigation focuses on known drug operations in the area but finds no match. At home, Skyler notices Walt is carrying extra cash and behaving erratically. She asks pointed questions about where he has been going, and Walt fabricates a story about winning money at a poker game with colleagues. Skyler is skeptical but lets it go for now. Jesse recovers from the beating and learns Walt made a deal with Tuco. He is both relieved and unnerved — Walt's transformation into someone who confronts violent criminals is something Jesse did not anticipate. They agree to cook Tuco's order immediately.