In Houston, Lydia, working at Madrigal's US office, receives a tip-off from Mike about the DEA coming to question her. Lydia manages to evade suspicion by selling out her patsy, Ron Forenall, with Mike promising to get her a replacement after the DEA leave.
Back at the White residence, Walt and Junior brag about their new cars (both of which Walt leased instead of buying outright to maintain his cover of having modest income) at dinner as Skyler silently eats her dinner, still fearful of her husband. The following morning, she almost neglects the family tradition of breaking Walt's bacon to form the number of his age on his birthday: "51".
At the DEA, Hank and Gomez go over diagrams of Gus's drug empire as they have hit a dead end: none of the men on Gus's payroll are saying anything, and "Blue Sky" is appearing on the streets once more. Hank is pulled aside for a moment by the standing Assistant Special Agent in Charge, who offers to promote Hank to ASAC in light of his having broken the case with Gus wide open, a promotion that Hank accepts.
Walt heads home early from a cook site with Jesse to celebrate his birthday. When he arrives home, he finds, to his disappointment, that Skyler brought home a pre-cooked dinner instead of cooking for him. Hank and Marie join them, and while Walt talks about how he has coped with cancer and how Skyler was a big support to him, Skyler slowly walks into the pool, as if to drown herself.
Walt rescues Skyler from her apparent suicide attempt and, after Hank and Marie go home, chastises her for being "shortsighted". Skyler adamantly demands that the children not be at home with them while Walt conducts his illegal enterprise, in spite of Walt's assurances that they were the safest they had ever been now that he was in charge. Walt asks Skyler how she intends to keep his own children away from him. Skyler suggests she have another self-injurious incident like at the pool, to which Walt counters that he would have her placed in a mental institute and raise the children by himself. Skyler states she will hurt herself and tell the police Walt abused her, but Walt shoots down that suggestion, stating that learning his father was a wife-beater would destroy Junior. Skyler claims she'll send Junior to boarding school, but Walt questions the wisdom in having Junior uproot his entire school life so late in the school year and be separated from his friends.
Skyler finally breaks down and admits she doesn't know what to do, that she can't even do anything. "I can't go to the police!" she cries. "I can't stop laundering your money, I can't keep you out of this house, I cant even keep you out of my bed! All I can do is wait. That's it, that's the only good option, hold on, bide my time, and wait."
"Wait for what? What are you waiting for" Walter asks.
"For the cancer to come back." Skyler answers.
Walt meets with Jesse and Mike. Jesse went to Madrigal's office in Houston some days earlier to pick up a barrel of methylamine, only to find that a GPS tracker had been placed on it. He talked the matter over with Mike, who states that the bug planting was too sloppy to be the DEA. Most likely, Lydia put the tracker on the barrel herself, to make them suspect that the DEA was tracking them so they would not try to use her as their connection. Mike prepares to leave to kill Lydia once and for all, but Jesse stops him and insists the three take a vote. Walt plainly states that the flow of methylamine was not to stop: they were going to proceed as usual, to Mike's chagrin.
Before Walt returns home, Jesse gives him a late birthday present: a new watch. Walt flaunts the watch to Skyler when he returns home, bragging of how Jesse wanted to kill him a few weeks ago, but how he managed to bring him back around, just like he believes he'll bring Skyler around.
This episode contains examples of:
- A Day in the Limelight: More Skyler-centric than most episodes. This is the same episode that Anna Gunn won an Emmy for Breaking Bad. Probably not a coincidence.
- Call-Back: When Walt and Skyler are arguing about how the children aren't safe:Walt: Gus Fring is dead. And he was the threat. He was the danger.Skyler: I thought you were the danger.
- Cathartic Scream: After the DEA's visit at Madrigal, Lydia retreats to her office, closes the blinds and screams in a pillow before calling Mike.
- Continuity Nod: To "Pilot", when Skyler arranges the bacon to form a "51" for Walt's birthday, albeit reluctantly this time.
- Cool Car: Walt and his newly-inflated ego buy a Chrysler 300 for himself and a Dodge Challenger for Walt Jr. (the same model he bought him in "Cornered" last season).
- Dissonant Serenity: The pool scene.
- Double-Meaning Title: It's Walt's 51st birthday. It could also be the point where Heisenberg is now the dominant ego in Walt's body.
- Driven to Suicide: Skyler fakes an attempt so she can get Walt Jr. and Holly away from Walt. Or was it faked?
- Ironic Birthday: Walt and Skyler celebrate his 51st (with a lampshade hung on how long a year it's been), celebrated for Walt Jr's sake despite the fact that he and Skyler are barely on speaking terms. Walt actually requests a "surprise" party along the lines of his last one, in an attempt to persuade Skyler that life is back to normal. Instead he gets a simple dinner with Hank and Marie during which Skyler tries to drown herself.
- Sherlock Scan: Gomez doesn't suspect Lydia of any involvement, but Hank catches that she mismatched her shoes, a mistake that suggests a level of stress that doesn't come from a clear conscience.
- Webcomic Time: Lampshaded by Marie:Walt: It was almost exactly a year ago that I got my cancer diagnosis.Marie: It seems like longer.
- Wham Line:Walt: For what [are you waiting for]?
Skyler: For the cancer to come back.
- Wouldn't Hit a Girl: Jesse pushes back hard against Mike's decision to kill Lydia.