Contains spoilers for this episode and earlier episodes.
Jesse travels to Mexico with Mike and Gus to teach the cartel to make their blue meth. The cartel's chemist doubts him, but Jesse produces a batch that impresses them. He is then told he belongs to the cartel; Mike says the arrangement is temporary. Back home, Walt misses Walter Jr.'s sixteenth birthday after his fight with Jesse. Walt's son finds him injured and disoriented. Walt blames gambling, apologizes and says he does not want to be remembered in that state. Walt drowsily calls his son Jesse. Walter Jr. stays overnight and later says he prefers this honesty to his father’s behaviour during the previous year.
Skyler arranges for Saul to send money to Ted under a false inheritance story so he can pay his tax debt. Ted spends it on a new car and his business, forcing Skyler to admit where the money came from. In Mexico, Gus poisons Don Eladio and his men with a bottle of tequila, then makes himself vomit. Gus is affected too. As the surviving cartel members react, Mike is shot and Jesse kills the gunman. Jesse drives Mike and Gus away from the residence, ending the episode with all three escaping. Gus had taken pills before the meeting and kept Jesse from drinking the tequila; even those precautions cannot prevent his own collapse during the escape.