Walt undergoes a combination of chemo and radiation treatment to shrink his tumor. He won't know the results of his treatments for four days, though, and he is left to dread the outcome as the scan of his chest reveals a large white spot on his lung...
At Saul's office, Walt receives a crash course in money laundering, a practice that Saul is exceptionally good at. After the costs of dealing with Badger's arrest, Walt is left with only about ten grand. Convinced that he may not have long to live, Walt decides to cook one more time to ensure he has something to leave behind for his family. To that end, he tells Skyler that he plans to visit his mother, to ensure that she can leave something for Skyler should the worst come to pass.
On Saturday morning, Jane suggests taking Jesse to an art museum. Jesse is on board with the date, but Walt throws a wrench into his social life, telling him that they are to do nothing but cook until Tuesday. Jesse balks at the idea, but eventually agrees when Walt explains that the methylamine is losing its potency.
Skyler drops Walt off at the airport that afternoon. After she leaves, Jesse picks him up in his RV, and the two drive out into the desert. Over the next two days, the two cook nonstop from dawn to dusk. They manage to cook up forty-seven pounds of meth, which would earn them well over half a million dollars each (approximately $400,000 each after paying Saul). Walt is determined to continue cooking, but Jesse, exhausted from working without rest, proposes taking the night off, checking into a motel, and having a meal at Denny's. Walt agrees to the break, but before they can depart, the battery in the RV dies: Jesse had left his key in the ignition for the last two days, draining the battery's charge, leaving Walt extremely cross.
The two try to use gas from the RV's tank to refuel the generator that powered their cook so they could jump-start the engine, but Jesse accidentally spills gasoline over the generator and causes it to burst into flames when he tries to power it up. Walt runs back into the RV to get the fire extinguisher, but Jesse dumps their remaining drinking water on the generator before he can put out the flames.
Now stranded in the desert, Jesse tries to get a cellphone signal on his phone to contact Skinny Pete for help, but to no avail. Walt's phone has a signal, but he is reluctant to use it since he suspects Skyler checks his call logs. He eventually relents and lets Jesse call on his phone, so Jesse can give Pete directions to their location. Unfortunately, Pete gets lost, and the phone dies when Jesse tries to redirect him.
The following morning, Walt tries to trickle-charge the RV's battery by hand-cranking the generator. Jesse realizes Walt lied about the methylamine spoiling. The process is slow and exhausting, leaving Walt weak and coughing blood, and ultimately proving fruitless as the engine fails to start. Walt falls into depression, stating that he deserved to die for all of the lies he told to cover his illegal activities. Jesse begs Walt to stop being pessimistic and think of something scientific that will get them out of their predicament.
Walt eventually comes up with one idea: a mercury battery using coins, galvinzed metal, and chemicals. The idea actually works, and the RV comes to life once more. Jesse drops Walt off at the airport afterwards, promising to make sure his family got their share of the profits.
Four days after embarking on his biggest cook yet, Walt visits his doctor with his family to get the results of his medical examines. To everyone's surprise, the tumor had shrunk by eighty percent! The white splotch on his scan? Just inflamation from the treatments. His coughing up blood? A rupture in his esophagus from all of his coughing, which can be treated.
After getting the good news, Walt goes to the restroom. As he leaves, he sees his reflection in a paper towel dispense. In anger, he punches his reflection, bruising his knuckles...
This episode contains examples of:
- Bait-and-Switch: The white spot and Walt coughing up blood? Lung inflammation and a tear in the esophagus (respectively), not because of the cancer.
- Blood from the Mouth: Walt starts coughing up blood in "4 Days Out". That is, until the end of the episode confirms that he's in remission.
- Bottle Episode: An odd example, in that the episode was supposed to be this, and it bears most of the hallmarks of such an episode (it takes place almost entirely in one location, and involves very little action), but the unexpectedly high number of outdoor shots ended up making it one of the most expensive episodes of the second season.
- Cutting the Knot / Stating the Simple Solution: Stranded in the wilderness due to the RV's battery running flat, Jesse frustratedly tries to coax Walt into figuring out a means of escape by MacGyvering something together. Among several laughable suggestions - including building a robot or an alternate vehicle from the RV's chassis - comes the sensible (and actually doable) notion of building a new battery out of the assorted contents of their rolling lab.
- Disaster Dominoes: Walter tells Jesse to not put the keys to the RV on the counter where they're cooking to avoid losing them so he puts them in the ignition which results in the battery dying. Then they try to use the generator to jump it but the generator catches fire (thanks to Jesse spilling fuel all over it) and Jesse uses the last of their drinking water to extinguish it right before Walter gets a fire extinguisher.
- Five-Second Foreshadowing: What does Jesse say in regards to his failed attempts at trying to start up the (gasoline-covered) generator? "It just needs to warm up a little." Then Jesse makes one last pull. Cue a spark.
- From Bad to Worse: They're in the middle of the desert and drain the RV's battery as their generator runs out of gas. Then the generator catches fire and they lose the last of their water and destroy the generator putting it out. Then their phones die. Then they trickle-charge the battery by hand-cranking the generator and the RV starts! And immediately dies. They finally get it to work after going to great lengths to build a makeshift battery out of various chemicals, bits of zinc, and several kitchen sponges.
- Hope Spot: Inverted. At first, it seems like the makeshift battery doesn't work... and then the engine roars to life.
- Played straight earlier when, having spent hours manually cranking the generator, Jesse gets the engine to start up for all of two seconds before it dies again.
- Locked in a Freezer: Walt and Jesse are stranded in the desert with no water and a flat battery.
- MacGyvering: Want to learn how to make your own battery? This is the episode for you.
- No Sense of Direction: Either Jesse gives bad directions or Skinny Pete is bad at following them, as he manages to cross a river when Walt and Jesse never came close to one.
- Oh, Crap!: For most people, news of cancer remission would be a time of elation. For Walt, it means his terminal excuse for meth making is gone. And now he's a healthy criminal, in deep with bad people.
- Rage Against the Reflection: Walt repeatedly punches his reflection in a bathroom tissue dispenser after hearing the news that his cancer is in remission. Ordinarily this would be good news, but for Walt, it means his "exit strategy" for getting out of the crystal meth business just vanished. There are multiple interpretations to his rage here, none of which are mutually exclusive. Along with the above, it also robbed of him of a convenient excuse to continue doing criminal deeds. This gained even more traction in the Grand Finale four years later when he admits that everything he did, he did because he enjoyed doing it.
- Shout-Out: When Walt and his family get the news that he's in remission, Hank joyfully quotes The Godfather Part III:Hank: "Just when I try to get out, they pull me back in!"
- Wham Episode: Walt's cancer goes into remission after he and Jesse cooked several pounds of meth in the desert.
- Wham Line: For Walt's family (and Walt especially), "Walt, I have your test results. You're showing signs of remission."
- And later in the same scene, "Walt, your tumor has shrunk by 80%."