You know what’s a real mystery? Who the murderer is in Vertigo Theatre’s It Could Be Any One of Us. That’s because the killer is determined at random in an onstage card game during the play, so there are a number of potential outcomes. So even if you’ve seen it, you don’t know whodunnit for sure. And your last chance to find out takes place takes place Sunday, Dec. 9 at 2 p.m., the closing performance of the comedic ensemble piece. (And it’s been getting above-average reviews, BTW.) Next up on Vertigo’s program is the noir classic Gaslight. It opens Friday, Jan. 26.