It's October 15, and it is indeed free. Go here for more information, and to get your tickets. You must be 21 and will be sent your code to get in 24 hours before the event via your mobile phone. Here's a video to let you know what you're getting yourself into:
Should be fun! I saw them in Chicago a few years ago at a sold-out show (was it the Metro?) and they were a lot of fun, and had LOTS of strobe lights. This is part of Southern Comfort's "Undercover Series", so it may be a little different as the band plays homage to some of their influences. The band will be in other cities, also, so check that web site for more info.