S4, E8: As Hank (Dean Norris) produces evidence that Gus (Giancarlo Esposito) is Albuquerque's meth kingpin, Walt (Bryan Cranston) worries that both he and Jesse (Aaron Paul) are going to be killed to protect their boss. Meanwhile, after refusing the Mexican cartel's demand to stop his drug trade, Gus returns to his roots as he fights back.