Previously on Breaking Bad: Oh God, it just all went to hell, didn't it? Skyler found out Walt dealt drugs, kicked him out of the house, softened, then invented an elaborate cover story and decided to help him launder his money through a car wash. Meanwhile, Jesse Pinkman downward spiraled like you wouldn't believe, but Walt bailed him out of a firefight with two dealers by killing said dealers with his Aztec of Destruction. By then, drug/fast-food kingpin Gus had quite enough with Walt's drama and was planning on killing him and replacing him with fellow chemistry whiz Gale. Walt caught on and the plan was to murder Gale, but he got waylaid by Gus's men (Mike the fixer and Victor the silent) and so it fell upon Jesse -- poor, (occasionally) sweet Jesse -- to save their lives by knocking on Gale's door and shooting him in the face. Also, at some point, Hank got shot and paralyzed. Holy shit.
Season 4 opens up with the traditional pre-credits short film, this time taking us back several months, maybe a year or so, to when Gus, Victor, and Gale were first assembling the industrial-strength meth lab that I've come to know as America's Meth Kitchen. Gale is opening the box of one of the big-ass meth vats by cutting the binding straps with a box cutter that not only is getting like six loving close-ups but also serves as the title of the episode. So, you know, file that one away. The look on Gale's face, by the way, is the unrestrained glee of a boy on Christmas morning (he even says as much to Gus). As was established last season, Gale isn't in this for the power or the money or -- God forbid -- the meth. He's in this for the science of it all. For the chance to cook the best he can cook. He produces a baggie of the blue meth for Gus -- a sample that Gus had asked him to get analyzed -- and declared that it's "quite good," at least in terms of sheer chemical purity. Gus tells him he can discard it, but Gale, in his own meek way, prods for more information. This is their competition, yes? Gus, ever the information hoarder, says as far as he's concerned, they don't have any competition. "After all," he smiles vacantly, "how pure can pure be?" As he walks away, Gale does maybe the bravest thing he's ever done and says, "...Pretty pure." He explains to Gus that what he can do, through diligent and hard work, is get their meth to about 96% purity. Which is great. But this blue meth that he just analyzed is 99% pure, maybe even a smidge more than that. And in that 3% lays a great bit of difference. Gus is still resistant to the idea, mostly because he has no respect for the man who produced it. "He's not a professional," he declares. Gale wonders aloud that if this man isn't a professional, he's not sure what that makes him. He says he's not trying to talk himself out of a job or anything, but he sees the lab Gus is assembling here, and he knows Gus wants the very best. So shouldn't he go after a man who can deliver that very best? It's no big secret what the show is doing with this scene. In the last microseconds of Gale's life, we're flashing back to a moment in time when he expressly advocated for the man who would ultimately be responsible for ending it. The irony is simple and it's cruel, and as Gale picks up Chekhov's Box Cutter and gets to work unpacking the next piece of equipment, we cut back to Gus's face. Also simple and cruel.