It’s one of the most evocative cold opens in recorded history. “Good evening everyone,” a voice intones. “You’re at Boston’s most intense underground dwelling, a lurid den of vice and l’amour…” The den of iniquity to which our unnamed tour guide is introducing us is The Rat, which over a thirty-year period played host to some of the most beloved, infamous, and/or unfortunately forgotten bands. Even after its demolition in the early oughts, punk fans spoke of it in mournful whispers, but it has only been eulogized in fragmented form. LET’S GO TO THE RAT (2013), a new documentary by Andy Szava-Kovats, seeks to set the record straight about the fallen venue.