They are the champions, Gleeks.

This Fox comedy celebrated a victory at Nationals last night, but the mood is about to get a lot more sullen next Tuesday, courtesy of the aptly-titled season three finale, "Goodbye."

The episode will center around graduating seniors and their post-William McKinley High School plans. It will also introduce Gloria Estefan as Santana's mom. Get your first look at what's ahead below via a trailer and a set of photos:

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.