TV tonight: 'Glee,' 'Fargo'

Glee | Fox, 8 ET/PT

There are many reasons for Glee's ratings collapse, from the inherent fickleness of its younger viewers (a group that tends to adopt shows fervently and drop them abruptly), to the casting changes that have weakened the ensemble. But as Glee shifts from its high school glee club roots to Rachel's Broadway opening night, you have to think part of the audience loss stems from precisely that shift: That a series that was once about a collective longing to fit in is now about an individual (and less relatable) search for stardom. As always, writers must be free to tell the story they want to tell — but choosing one viewers don't want to hear is never a wise ratings move.

A Fierce Green Fire | PBS, 9 ET/PT (times may vary)

American Masters offers the TV debut of this documentary examining the history of the environmental movement. Robert Redford, Ashley Judd, Van Jones, Isabel Allende and Meryl Streep serve as narrators.

Fargo | FX, 10 ET/PT

When a show begins as well as Fargo did with its almost preternaturally entertaining premiere, it's natural to wonder whether a letdown is on the way. Fans, then, should find tonight's excellent second outing incredibly reassuring, as the plot takes an intriguing new twist and the show adds two more engagingly eccentric characters: offbeat enforcers played by Adam Goldberg and Russell Harvard.