We open on a young teenage boy riding his dirtbike over rural desert in New Mexico. He comes across a tarantuala and allows it to harmlessly crawl over his hands, then places it in a glass jar and puts in in his pocket. Way off in the distance, we hear a freight train, which draws the boy to ride over to it. Cue the title card.
Walt pays a visit to Hank's new office and, once they're alone, begins tearfully venting about his and Skyler's broken marriage. When Hank, extremely uncomfortable, leaves the office for a moment to get Walt a cup of coffee, Walt uses the opportunity to plant a bug on his desk.
Afterwards, Walt, Jesse, and Mike pay a visit to Houston, where they abduct Lydia and take her to an abandoned building. Mike explains that he is giving Lydia a chance to redeem herself on behalf of his associates; he asks her to quickly memorize a script while he calls the Albuquerque DEA to figure out whether they had really placed tracking devices on Lydia's methylamine inventory, or whether Lydia had planted them herself to scare Mike off of her supply. If he didn't like what he heard, or she deviated from the script or started crying, he would pull out his pistol and shoot her in the head.
Lydia, reading off the script, asks Hank about the tracking devices, but Hank claims to know nothing about them. While he puts Lydia on hold to double check with the Houston DEA office, Mike reiterates that they would be better off killing Lydia and sparing themselves any further trouble. Jesse tries to convince Mike otherwise, but unfortunately, Walt agrees; the vote is two to one to kill Lydia.
As Lydia desperately begs for her life, the bug in Hank's office confirms her innocence; someone in the DEA had, indeed, put trackers on Lydia's supply, albeit without Hank's knowledge. Worse still, all of the barrels in her inventory have been tagged, which means they'll need to find a new connection. As far as Mike is concerned, this means Lydia still needs to die. Lydia, however, suggests an idea that might just work and save her own life in the process; stealing methylamine directly from a train tanker, a veritable "ocean" of methylamine. Her work lets her know what train will be transporting methylamine, which car it is in, what time it is expected to arrive at its destination, and the path it takes. As the train passes through New Mexico, it will enter a radio dead zone wherein no red flags would be raised if it came to a sudden stop. In exchange for this information, Lydia asks Walt for his word that she won't be killed, in addition to a cut of the profits.
As Walt's family life continues to fall apart—he agrees to let the children remain at the Schraders' for safety in exchange for Skyler's cooperation in his double life—Walt, Jesse, and Mike discuss Lydia's proposal. Mike is certain any such plan will fail and end in their arrest or death if they aren't willing to kill the train conductor and engineer to avoid leaving witnesses. He suggests scaling back their operation to a pseudoephedrine cook. Walt is unwilling to scale back, and bitterly reminds Mike of the "hazard pay" they already have to dish out to Mike's nine guys in prison to keep them from talking. As Walt and Mike argue, Jesse has an epiphany: "What if we can rip off that train...and no one ever knows it got robbed?"
Walt, Jesse, and Mike put their new plan into motion. As two members of the Vamanos Pest exterminator crew dig a pit next to the train tracks to place a tanker for storing their soon-to-be stolen methylamine, Walt and Jesse explain to Todd Alquist, another exterminator who will be helping them with the heist, that the plan is to syphon methylamine out of the tanker car while replacing it with water to keep the weight consistent. Even though this will make the methylamine remaining in the tanker slightly diluted, no one would suspect a theft; Madrigal would simply blame their Chinese manufacturer for sending weaker methylamine. Jesse then tells Todd that, because they'll be committing a major felony, no one can ever know about the heist.
On the day of the heist, Patrick Kuby, one of Saul's employees, blocks the train's path with a "broken-down" truck. As Mike serves as lookout while the conductor and engineer try to get the truck running again, Jesse runs under the tanker to syphon the methylamine while Todd pumps water in from the top and Walt monitors their progress at the tanks. But the plan is derailed by a Good Samaritan who offers to push Kuby's truck out of the way, which Kuby can't decline without drawing suspicion. Mike tells Walt to abandon ship with the hundreds of gallons of methylamine they've already gotten, but Walt insists on keeping Jesse and Todd on the train until they get exactly 1000 gallons. They cut it so close that Todd has to jump off the moving train, which runs over Jesse while he stays flat against the tracks, but the heist is ultimately a success and the train crew is none the wiser.
As they celebrate their victory, however, they notice that they had been witnessed by a young boy, watching them from atop his dirt bike, last seen in this episode's Cold Open.
The boy waves at Walt, Jesse, and Todd.
Todd casually waves back. Without any change in his expression, he then draws his gun. Jesse, realizing what Todd is about to do, quickly yells out a panicked protest, but undeterred by this, Todd shoots the boy and kills him on the spot.
This episode contains examples of:
- Anyone Can Die: Even a kid who has nothing to do with the plot of the episode.
- Ascended Extra: Todd initially was just one of the Vamonos Pest employees. Now he helps Walt and Co. on bigger jobs, and in a matter of seconds completely changes the course of the whole story.
- As You Know: Walt and Jesse explain to Todd how the train robbery will go and why they planned it out as such, while they're in the middle of setting everything up. Justified, as Todd was just recently brought over and hadn't been given the details yet.
- Big "NO!": Jesse, right as Todd points the gun at Drew.
- Call-Back: Walt uses the word spillage for spilled methlamine while planning out the heist with Jesse and explaining it to Todd. This is the same term Jesse used in The Fly as a possible explanation (lie) for why their numbers were down when they worked for Gus.
- Cassandra Truth: Lydia's pleas that she didn't place the bug fall on deaf ears, and Mike is just about ready to waste her when their surveillance picks up a conversation with Hank and one of the agents revealing that it was one of them who placed it.
- Chekhov's Gunman:
- The young boy in the Cold Open turns up at the heist at the end to be killed by Todd.
- This episode serves to bolster Todd's importance in the story, after he first appeared as just another employee for Vamanos Pest.
- Crazy Enough to Work: Jesse once again comes up with such a plan. This time, to avoid Mike's worries over security and witnesses and to satisfy Walt's insistence on staying with his methylamine formula, Jesse suggests how they can rob the train without anyone ever knowing.
- Establishing Character Moment: In his first mission out with Walter and Jesse, Todd murders a child in cold blood just because the child saw them (and Walt said earlier that no one can know they were there).
- Exact Words: Todd takes Walt extremely seriously when he says that there are to be no witnesses to the robbery.
- Faking Engine Trouble: This was done with a dump truck to get a train to stop so they could steal methylamine from one of its cars without getting caught.
- Foreshadowing: Todd's early comment of "Damn, you guys thought of everything," and before it, Walter insisting that absolutely no one other than the crew can be aware that the robbery happened, both serve as Tempting Fate.
- Fun with Subtitles: A variation. In Hank's office, Walt makes up a name for a psychiatrist Skyler is supposedly seeing. At the moment Walt says, "Peter," co-exec producer Peter Gould's credit appears on the screen.
- Gone Horribly Right: Mike states there's only two kinds of heists: unsuccessful ones, and ones successful because they leave no witnesses. This is a successful heist... And it's horrible why.
- Good Samaritan: One arrives on the scene and offers to push Kuby's truck off the tracks with his, almost ruining the crew's plan.
- Hope Spot: The train heist goes off more or less without a hitch, and the group are celebrating. Then they realize they've been watched...
- Insistent Terminology: If Lydia makes a wrong move, Mike will take his pistol and shooter her in the head, not his gun.
- Knight of Cerebus: Every single scene with Todd in it from this episode onwards loses any sense of levity the show still has left.
- Leave No Witnesses: Discussed. Mike points out that if they go in guns blazing to rob the train, they will have to kill the crew or face the certainty of getting caught. To avoid this, Jesse comes up with an elaborate scheme that will allow them to rob it without being noticed. Unfortunately, Todd takes the concept to heart a bit too closely.
- Little "No": Jesse, right after Todd shoots Drew.
- Mood Whiplash: Walt, Jesse, and Todd have just barely managed to pull off the train heist without getting caught. They are celebrating, everything is triumphant ... and turn to notice they were being watched by a kid on a dirtbike. Which Todd then kills.
- Real Stitches for Fake Snitches: Everyone's ready to kill Lydia under suspicion of her being responsible for planting bugs under their barrels of methylamine, until she calls the DEA and clears her name.
- Sarcastic Confession: Walt telling Skyler that he plans to rob a train seems comes off as one due to how outlandish it sounds, but Skyler knows that Walt is fully capable of doing such a thing.
- The Scapegoat: Even though the company will eventually discover the watered-down quality of their methylamine at their next stop, Walt and the others anticipate them blaming China as responsible for supplying low-quality cargo with no way to figure out they were robbed.
- Snark-to-Snark Combat: After getting Walt Jr. out of the house and discussing their current situation:Skyler: (seeing Walt with dirt on his pants) Out burying bodies?
Walt: Robbing a train.
- Spanner in the Works:
- The bug placed on the bottom of the methylamine barrel turns out to indeed have been the DEA's work, who actually put them on all the barrels. Their sloppy placing of it means that Lydia was able to detect it immediately, and Hank is ready to give them an earful for not informing him about it.
- The Good Samaritan that helps the truck get off of the train tracks results in the train being able to move far ahead of schedule. As a result, Jesse gets stuck on the tracks until the train leaves and Todd almost doesn't get off the top before the train reaches top speed.
- The ending has two. The boy who sees the robbery is one for the plan to rob the train undetected, and in terms of the metaplot, Todd proves to be the Spanner that disrupts the fragile working alliance between Walt, Jesse, and Mike.
- Sudden Downer Ending: The boy's murder.
- Train Job: Complete with Shout Outs to a number of classic Westerns.
- Wham Episode: Walt and Jesse assemble a crew to pull off a train heist, and just barely get it done in time. While celebrating, a kid riding through on a dirtbike sees them, causing Todd to quickly pull out his pistol and shoot the kid as Jesse protests, following the creed of "no witnesses."
- Would Hurt a Child: Todd Alquist shoots 14-year-old Drew Sharp for accidentally stumbling across their heist.
- You Have Outlived Your Usefulness: In one of the rare occasions in which Mike and Walt are on the same page, both want to do this to Lydia when she becomes unable to supply the methylamine she she promised.