What Happens: After learning he has lung cancer and just a few years to live, Walt gets an interest in the meth business and enlists Jesse for his first cook. Things go sour, and Walt ends up killing Emilio and knocking out Krazy 8 after they threaten to kill him. Why it's the best: It clearly maps out the ingredients needed for Walt's journey from Mr. Chips to Scarface. The episode shows us the protagonist's ineffectual existence as Walter White and the first inklings of Heisenberg.
Season 2, Ep. 12 ('Phoenix')
What happens: Jane learns that Walt is holding on to the $480,000 he owes Jesse and blackmails Walt into delivering the sum. After stopping at a bar and unknowingly talking to Jane's father, Walt returns to Jesse's and fails to help Jane as she chokes to death on her own vomit. Why it's the best: When exactly Walt loses his soul is a favorite topic among Bad fans. This episode contains as good a moment as any. Jane's death would go on to loom large in the series, all the way until the end.
Season 3, Ep. 7 ('One Minute')
What happens: Hank is put on leave from the DEA after beating Jesse to a pulp. Hank, unarmed, receives a call that two men are coming to kill him and he has just one minute to prepare. Why it's the best: THR readers voted (by a landslide) the "One Minute" ending as Hank's finest moment. The tension, and the unprecedented level of action, were off the charts. Hank's nearly fatal injuries would set up Dean Norris for an amazing run in season four as the recovering (and mineral-obsessed) Hank.
Season 3, Ep. 12 ('Half Measures')
What happens: Jesse plots the murder of the drug dealers who ordered young Tomas to kill Combo. Gus catches wind of this, and calls a meeting between the dealers and Jesse and orders him to end the feud. Later, Jesse learns from Andrea that Tomas has been killed. He goes to shoot the dealers, but Walt runs them over first. Why it's the best: Walt's murder of the dealers and telling Jesse to "Run" is one of the most shocking moments in Bad history. Let's not forget Mike's amazing "no more half measures" speech (which inspired Aaron Paul to get a half measures tattoo.)
Season 3, Ep. 13 ('Full Measure')
What happens: Walt knows that Gus will kill him as soon as Gale is able to take over the superlab. He asks Jesse to find out where Gale lives so Walt can kill him. Later, Walt is brought to the superlab by Victor, and knows he is about to be executed. He tricks Mike into letting him call Jesse, and then orders Jesse to kill Gale. Why it's the best: The murder of Gale simultaneously shows Gus just how dangerous Walt is and destroys Jesse's soul. The shocking season finale – one of many for Bad – perfectly sets up the adversarial relationship between Gus and Walt in the excellent fourth season.
Season 4, Ep. 11 ('Crawl Space')
What happens: Jesse tells Gus he won't cook if Walt is killed. Meanwhile, Skyler has Saul force Ted to write a giant check to the IRS – using Walt's money. Later, after Gus threatens Walt's family, he frantically seeks that very money to pay Saul's disappearing guy. Why it's the best: Walt cackling like a mad man in his crawl space is more than enough to push this episode over the edge. But it's also got Gus' amazing "I will kill your wife, I will kill your son, I will kill your infant daughter," speech.
Season 4, Ep. 13 ('Face Off')
What happens: Walt teams up with Hector to take out Gus, and rigs a bomb to go off when Hector rings his bell. Gus comes to Hector's nursing home to kill him and has half of his face blown off when a vengeful Hector detonates the bomb. Why it's the best: This is Walt at his most brilliant, and he outsmarts his most formidable opponent in an incredibly surprising way. The episode also marks a huge turning point for how we view Walt, who we learn has poisoned a child. When he tells Skyler "I won," it's a pure Heisenberg moment. There's an arrogance in the way he says it, and that arrogance would carry over into the coming episodes in a big way.
Season 5, Ep. 5 ('Dead Freight')
What happens: Jesse and Walt's plan to rob a train full of Methylamine is a success, until a boy on a dirt bike comes across them, and Todd shoots him. Why it's the best: This episode is really fun, and the train heist feels like a classic Western. The moments immediately after the heist are the last time we see Jesse and Walt happy in each other's company. But in classic Bad fashion, the happy moment doesn't last, as the murder of young Drew Sharp becomes the last straw that drives Jesse and Walt apart.
Season 5, Ep. 7 ('Say My Name')
What happens: Walt makes an amazing speech and gets Declan to buy out Mike's share in the partnership. Walt still wants Jesse to cook with him, but he refuses, so Walt begins cooking with Todd instead. Meanwhile, Mike's lawyer is arrested and decides to rat him out. Walt demands to know the name of Mike's men in prison, and when Mike refuses, Walt murders him in anger. Why it's the best: It starts with one of Walt's most amazing speeches ("You're goddamned right!") and ends with one of his most terrible acts -- killing Mike for no reason. If you're still rooting for Walt at this point, we have to wonder why.
Season 5, Ep. 14 ('Ozymandias')
What happens: Hank dies. The Aryan gang steals most of Walt's money. Walt confesses his role in Jane's death and lets the gang take Jesse. Walt Jr. learns the truth about his father, and calls the police after his parents get into a knife fight. Walt abducts baby Holly and then calls Skyler (knowing the police are listening) and confesses his crimes. He leaves Holly at a fire station and calls Saul's disappearing guy, who takes him away to give him a new identity. Why it's the best: Years of storytelling come to a head for this episode -- and it's executed flawlessly. Plus, Vince Gilligan says it's the best episode of the series.