Having bought the blue meth from the gang responsible, confirming that Combo's killers work for Gus Fring, Jesse tells Walt and asks him to make ricin to exact revenge.
Mike Ehrmantraut makes an unannounced visit to Walt at home and reveals he also works for Gus, who would "take it as a problem" if Jesse would be jailed.
Mike then tells Walt a story from his years as a cop, in which he laments over showing mercy to an alcoholic, continually-abusive husband who subsequently killed his wife.
Aaron Paul won the Primetime Emmy Award for Outstanding Supporting Actor in a Drama Series for his performance in this episode.
[1][2] In IGN's review, the episode is called "fun, creative, well-directed, well-acted and set us up for what's going to be an awesome finale", and was given a 9.7 rating.