Brown Betty (Fringe)

"Brown Betty" is the 19th episode of the second season of the American science fiction drama television series Fringe, the 40th overall episode of the series, and is the only one of the series performed as a musical. The episode was written by co-showrunners Jeff Pinkner and J. H. Wyman, and consulting producer Akiva Goldsman. It was directed by filmmaker Seith Mann. As the episode begins with Peter's continued disappearance, Walter consoles himself by smoking a strain of marijuana called "Brown Betty." Most of the episode is then told from his drug-addled perspective, in which Olivia is a 1940s noir detective and Peter is a conman who ran away with Walter's glass heart.

The episode first aired in the United States on April 29, 2010 on the Fox Broadcasting Company and was seen by 5.551 million viewers in the United States. The episode was part of the network's "Fox Rocks" campaign, in which musical elements were incorporated into various shows in their lineup for a week, a concept that was panned by critics before the episode aired. Nevertheless, "Brown Betty" garnered mostly favorable reviews, with many noting the musical element as a strong point. Various cast members also stated that they enjoyed the musical aspect of the episode. It was ranked the fourth best episode of the entire series by Entertainment Weekly.