As per Mike's suggestion, Walt pays a visit to Hank's new office. When Hank leaves the office for a moment to get Walt a cup of coffee, Walt uses the opportunity to plant a bug.
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 called the Albuquerque DEA to confirm where the tracking bug on the barrel they meant to pick up came from. 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.
When Lydia asks Hank about the origins of the tracking device on the barrel, Hank claims to not know where it came from. While Hank puts Lydia on hold to check on where the bug came from, 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 statements; someone in the DEA had, indeed, put the bug on the barrel, albeit without Hank's knowledge. Worse still, all of the barrels had been similarly 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 hide in the process; taking 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 would take. As it passed through New Mexico, it would 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 would not die, in addition to a cut of the profits.
As Walt's family life falls apart as he agrees to let the children remain at the Schraders in exchange for Skyler's cooperation, Walt, Jesse, and Mike discuss Lydia's proposal. Mike is certain any such plan would fail and end in their arrest or death on account of having to dispatch the train engineers to deal with witnesses. He suggests scaling back their operation to a pseudoephedrine cook. Walt, unwilling to scale back, brings back up the "hazard pay" for Mike's crew in prison, suggesting Mike's proposal was only to pay off the men lest they talk to the police. As Walt and Mike argue bitterly, 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 exterminator crew dig a pit to place a tanker for storing the methylamine, Walt and Jesse explain to Todd Alquist, another exterminator who fills the tank with water, that the plan is to syphon methylamine out of the tanker car while putting water back in to keep the weight consistent, a feat that could be accomplished by draining the methylamine out the bottom of the tanker due to it being slightly heavier than water. Even though this would make the methylamine remaining in the tanker diluted, no one would be any wiser; Madrigal would simply blame their Chinese manufacturer for sending weaker methylamine. Jesse then states to Todd that, because they would be committing a major crime, 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" car. As Mike serves as lookout, Jesse runs under the tanker to syphon the methylamine while Todd pours water in from the top and Walt monitors the progress of their caper. The plan is almost derailed by a Good Samaritan who offers to push Kuby's truck out of the way, which Kuby can't decline without drawing suspicion. In the end, however, the plan succeeds; while they cut it close, the crew manages to steal a thousand gallons of methylamine, with the train crew being 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.
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 once, killing him on the spot.
This episode contains examples of:
- 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.
- Big "NO!" Jesse, right as Todd points the gun at Drew.
- 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.
- 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 taking Walt extremely literally 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.
- 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.
- Foreshadowing: Todd's early comment of "Gee, 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.
- 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...
- 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.
- 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 then Todd kills a kid.
- 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.
- Snark-to-Snark Combat:Skyler: (seeing Walt with dirt on his pants) Out burying bodies?
Walt: Robbing a train.
- Spanner in the Works: Two of them. 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.
- 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 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.
- 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.