Gus, Mike and Jesse are flown in to Mexico to start work for the cartel. Meanwhile, Walt Jr. is having his 16th birthday and his dad is a no-show as he is recovering from his fight with Jesse in the last episode. Ted, still in debt to the IRS, suddenly gets an inheritance equal to what he owes them from Saul.At the Mexican plant, the local chemist had doubts about Jesse as a cook, as he is unable to synthesize an essential acid for making meth. However, Jesse assures them that he is the only one there who can create the perfect product, and puts their fears to rest when his sample reads with a 96.2% purity. However, he is dismayed to find out that he is being given to the cartel to cook for them. Walt Jr. then goes to check up on his dad, who is driven to tears over the guilt of missing his son's birthday. As this happens, Saul informs Skyler that the "dead aunt" money given to Ted has been put to frivolous use.Walt Jr. stays the night with his dad to make sure he's okay, and Walter White talks about how his only memory of his dad was not a happy one - something he fears this indecent will do to the relationship with his son. Skyler also pressures Ted into using the money he has to settle with the IRS, but he refuses. Frustrated, she reveals that she was the "dead aunt" he got it from.To celebrate the success of the new cook and amends made by Gus to the cartel, Don Eladio and his men celebrate with a gift from Gus in the form of an expensive spirit. It turns out to be poisoned and leaves all but one of his men dead - the remaining one taken out by Jesse. Despite an antidote and forced regurgitation, Gus is also affected by the poison, Mike has been shot, and Jesse has to drive them away.
This episode contains examples of:
- Acquired Poison Immunity: Beforehand, Gus took an antidote and later activated his gag reflex to avoid the effects of the poisoned drink. Subverted, as he was still weakened by its effects.
- Freeze-Frame Bonus: As Jesse, Mike, and an unconscious Gus are hopping in a car to escape, you can see for a split second that Mike is about to shoot Jesse while his back is turned, right before Joaquin Salamanca appears and shoots at him.
- Self Poisoning Gambit: Don Eladio and his capos refuse to drink the poisoned tequila until Gus does, so he goes ahead and drinks to ensure that they will.
- Unexpected Inheritance: How Skyler lends the money to Ted to fix his problems with the IRS. Saul admits he didn't think that would work. Of course, Saul probably meant it in the sense of "the story wouldn't be believable", not as in "he'll probably not realize that the money is meant to pay his taxes".
- Wrong Name Outburst: Walt accidentally calls Walt Jr. "Jesse" after he drifts off on painkillers.
- You Have Outlived Your Usefulness: Mike was planning to do this to Jesse until Joaquin Salamanca started attacking.