So much of the play “Enron” is true to life, that to call it a dark comedy, you must emphasize dark, or as a cautionary tale, a better emphasis would be: beware. Quantum Theatre is retelling the tale right on time for the demon season, with a compelling, kinetic staging of the Lucy Prebble play that looks back on the downfall of a corporate giant. The Texas-based energy company was known to all who lived through the turn of the 20th century for its national “Ask Why” campaign, which portrayed Enron as a pioneering, innovative energy and business company. It was all smoke and mirrors, laid bare in the compelling production, a collaboration with Attack Theatre.