THE SIMPSONS “500 Keys” Season 22 Episode 21 May 15, 2011 News, The Simpsons Episode Synopsis: When the Simpsons discover a collection of keys to every door in Springfield, Lisa stumbles upon an eerie hidden classroom beneath Springfield Elementary School. When she shares her discovery with Principal Skinner, the secret room mysteriously disappears and he takes the only key away. A determined Lisa uses her detective skills to lead her back to the room to solve an old school mystery in the all-new “500 Keys” episode of THE SIMPSONS airing Sunday, May 15 (8:00-8:30 PM ET/PT) on FOX. Click Any Photo Below To Enlarge Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Reddit (Opens in new window)Click to share on Google+ (Opens in new window)Click to share on Tumblr (Opens in new window)Click to share on Pocket (Opens in new window)
