The Cold Open shows several close-up shots of a house fly buzzing around while Skyler's voice sings a lullaby.
Walt's morning alarm goes off, but he's already awake and clearly has been all night. He and Jesse arrive at work to clean Gus' superlab. Walt's calculations on their meth yields seem to be off, though: they're coming up consistently short. Jesse, trying to keep Walt from realizing that he's skimming meth from each batch to sell on his own, suggests spillage, evaporation, and other causes for their product's yield being low, but none of them make sense.
After Jesse punches out for the day, Walt notices a fly in the superlab. Worried about contamination, Walt tries to kill the fly, but his every attempt fails, with one attempt causing him to fall from the above walkway and badly hit his head. The fly lands on one of the lenses of his glasses, almost as if taunting him...
When Jesse returns to work the next day, he's saddened after noticing a cigarette butt with a lipstick smudge still in his car. He sees that Walt's car is still parked outside the laundromat. When he enters the lab, his ears pop as a result of increased air pressure that Walt subjected the lab to in order to contain the "contamination". Jesse is freaked out, but when Walt finally states that the contamination is only a house fly, Jesse is left confused and exasperated: Mr. White is getting this worked up over a fly?! When Jesse tries to cook, Walt commands him to stop, and hits him with his homemade fly swatter. After Jesse, at Walt's request, whacks Walt in the head with the swatter after the fly lands on him, Walt explains that there is no more room for error when dealing with Gus: if they cannot clear out the contamination, they're as good as dead.
Jesse tries to tell Walt that they should step out for air and clear their heads, but Walt takes Jesse's lab keys and banishes him from the lab: "If you're not gonna help me, stay out of my way!" he barks. Jesse counters by shutting off the laundromat's main breaker to regain entrance.
When Jesse returns to the lab, he brings fly paper. He also brings some sleeping pills to slip into Walt's coffee so that the clearly-unstable Walt can get some sleep.
While waiting for the fly to get caught in one of the fly paper strips, Jesse tells Walt about "Scrabble", a possum that had been found under his aunt's house that used to cause a ruckus. Even after the possum was removed, his aunt was convinced that "Scrabble" was still under the house making noise. It was a sign that her cancer had metastasized and spread to her brain.
Walt tells Jesse that he has been to his oncologist and is still in remission. As the sleeping pills begin to take effect, he confides in Jesse his belief that he's "lived too long," and begins wondering what the perfect moment for him to die could've been. He's wracked with guilt and sorrow over the lies he's had to tell, and the fact that he cannot seem to make Skyler understand that he is cooking meth for the sake of his family.
He tells Jesse how he had met Jane's father on the night that she died: the universe may be random, but how could it be random that he wound up in the exact same bar as Donald Margolis on the very night that Jane overdosed? As he becomes drowsy, he recalls hearing his wife singing a lullaby to their daughter just before Walt had left to give Jesse the money Jane had been blackmailing him for, and, unbeknownst to Jesse, where he had let Jane die from a heroin overdose. If he had just passed away at that moment, having made enough money to support his family after his death without them ever finding out about his meth cooking, it would've been perfect...
Jesse sees the fly on the ceiling and precariously sets up a ladder so that he can try to swat it. Walt tells him he'll break his neck, so Jesse tells him to hold the ladder steady. As Jesse spots the fly and prepares to swat it, Walt, half-asleep, begs Jesse to come down and apologizes for Jane. Jesse, not realizing Walt was confessing to letting Jane die, tells him it's not his fault: no one could've stopped Jane from overdosing.
Conceding that "it's all contaminated," Walt tells Jesse to forget about the fly and finally falls asleep. Jesse sees the fly one last time as he's climbing down from the ladder and manages to swat it, killing the pest once and for all. He turns in excitement to Walt, only to realize he'd fallen asleep. Jesse lays Walt down on the couch outside their lab and finishes the cook on his own.
The two return home the following morning. In the parking lot, Walt pulls Jesse aside and talks to him: he suspects Jesse may be stealing some of their product, but didn't want to say anything in the lab in case it was rigged with microphones. While he never outright accuses Jesse, he warns him that if he is and Gus finds out, Walt wouldn't be able to protect him.
Jesse coldly tells Walt that he didn't steal anything before he leaves. Later that night, Walt lies in bed, seemingly unable to sleep, when all of a sudden, a familiar irritating buzzing reaches his ears...
This episode provides examples of:
- Absentee Actor: The entire cast save for Walt and Jesse.
- Bait-and-Switch: Two different times, Walt comes within an inch about telling Jesse that he watched Jane die, but he stops himself the first time and the second time Jesse misinterprets him.
- Bottle Episode: With the exception of the opening and closing scenes, the entire episode takes place inside the lab. Only Walt and Jesse appear in it, although we also hear Skyler's voice through the baby monitor. And even then, it's reused audio from "Phoenix".
- Breather Episode: It's also a self-contained episode that doesn't advance many story arcs beyond Walt's suspicion that Jesse is pocketing some of the pocket, and acts as a soft cushion before all of the subsequent drama that is about to ensue.
- Closed Circle: Jesse and Walt are trapped in an airtight lab trying to kill a fly to prevent contamination; since they can't cook meth with the contaminant, and they can't leave until they've cooked, they spend the episode trapped.
- "Could Have Avoided This!" Plot: Discussed when Walt starts trying to pinpoint the moment where if he'd just died, he would've left his family enough money without causing them any further danger.
- Death Glare: As seen in the page image, Walt gives the fly in the lab a really mean look when it lands on his glasses.
- Despair Event Horizon: Walt lampshades this while talking to Jesse about finding out about his cancer being in remission. He would've much preferred if he succumbed to the cancer after his daughter's birth. It's implied that this ideal death would enable Walt to avoid any heavy consequences with his drug manufacturing, but with the remission, Walt will probably be alive a little longer than he assumed.
- Does This Remind You of Anything?: Walt is hunting a fly that he views as a filthy contaminant. During the hunt, Jesse dons his safety gear and tries to keep cooking. His facemask is propped in such a way as to put two large, red bulbs on top of his head — just like the fly's eyes. Walt even smacks him with his improvised flyswatter.
- El Spanish "-o": When Walt locks him out of the lab, Jesse asks the laundromat workers for "el axe-o".
- Epic Fail: Walt discovers a housefly in the meth lab. He begins trying to swat the fly, but it's just too fast for him. Growing increasingly frustrated, he spots the fly on the ceiling and throws his shoe at it and ends up breaking an overhead light, raining glass down on himself and getting his shoe stuck in the light fixture. Then, he goes up on the catwalk and over the railing to dislodge his stuck shoe, spots the fly on the railing he's hanging from and attempts to have a swing at it... and falls off the catwalk, slamming into a vat and landing painfully on the floor. Just to make things worse, the fly then lands on his glasses. That's right: Breaking Bad did slapstick comedy.
- Even Evil Has Standards: Arguably taken too far with Walt, who refuses to cook a batch of methamphetamine — one of the most harmful and addictive drugs that there is — because a fly may contaminate it. Jesse lampshades the absurdity of this:Jesse: We make poison for people who don't care, alright? We probably have the most un-picky customers in the world.
- Fly Crazy: Walt goes to comical lengths to get the fly out of his lab.
- For Want of a Nail: During the Motive Decay moment listed below, Walt says that he should never have left home and gone to Jesse's apartment. He then quietly states that things could've been different if that were the case. Jesse, however, points out that doesn't necessarily mean things would have turned out better, and that he and Jane would likely have ended up either dying from an overdose, or being killed for their money.
- Here We Go Again!: The episode ends with Walt finding a new fly on his smoke detector.
- Internal Reveal: A past example; Walt realized a long time ago after the plane explosion that the man he talked to in the bar the night of Jane's death was her father after seeing his face on the news. Also narrowly subverted when talking about this almost causes Walt to reveal to Jesse his witnessing her death.
- In Vino Veritas: When Walt is drowsy thanks to his sleeping pills, he opens up about how he should be dead by now and would have preferred to succumb to his cancer. He also almost tells Jesse his role in Jane's death, but it's subverted when Jesse misunderstands what he was saying.
- Laser-Guided Karma: Walt smacks Jesse upside the head with his homemade flyswatter to stop him from opening one of the vats, which Jesse gets to immediately payback when the fly lands on Walt's head and Walt tells him to "make it count".
- The Last of These Is Not Like the Others: In the list of reasons why he should still live, Walt tellingly adds the birth of his daughter as an after-thought, seeming to place more importance on the first million he made as a reason to have not dropped dead.
- Locked in a Freezer: Walt and Jesse are trapped in the lab, unable to cook until they manage to decontaminate the lab (i.e., kill one of the most daring flies on television). They're stuck there until they can kill the fly and cook the batch.
- Motive Decay: Pointed out by Walt himself; he only needed enough money to leave behind once he died. Once he went into remission and started working for Gus, it started to not make sense.
- Specifically, Walt states that had he died listening to Skyler singing to Holly over the baby monitor (back in "Phoenix"), then it would've been the "perfect moment" for him to stop.
- Mundane Made Awesome: Never before has killing a fly been so satisfying.
- Neat Freak: Walt panics over a fly in the lab.
- One Degree of Separation: Walt muses on how unlikely a coincidence it was that he would meet Don Margolis at the bar, even more so given that the very same night, Walt would go on to watch Jane Margolis asphyxiate on her own vomit.
- Obfuscating Insanity: It seemed that Walt was faking his obsession over the fly to draw attention away from him confronting Jesse over some stolen meth. Though in the end when he sees a fly on his smoke detector, he might have not been all the way faking it.
- Pest Episode: A lone errant fly in the lab sets the whole episode in motion.
- Serious Business: You can't have a fly in your meth lab; it taints the product.
- Worthy Opponent: The titular insect, according to Jesse.Jesse: He's got skills, yo. I'll give him that.