When Balagan Theatre nabbed the rights to Dr. Horrible’s Sing-Along Blog last year, the fringe troupe felt lucky but had serious work to do before any funny business. The three-act comedy, a 2008 Internet/DVD sensation unleashed by Buffy the Vampire creator Joss Whedon, features wacky original pop tunes that sweeten the amusing tale of a would-be evil scientist who hopes for—what else?—total domination of the planet…and, sure, also the love of that cute girl in the Laundromat. (“I’ll bend the world to our will,” Dr. Horrible sings, “And we’ll make time stand still.”) Yet Whedon and Co. provided free rein without script or score to Balagan, whose founder/executive director, Jake Groshong, had his crew transcribe dialogue before devising harmonies and instrumentations. Thus what he calls “a hyped-up version of what you see online,” with songs interspersed from Commentary! The Musical, the equally amusing and tuneful commentary track from the Horrible DVD. This helped expand the original 45-minute show into an hour-and-a-half of hilarity. Balagan’s effort paid off: The first Horrible run sold out all 15 performances. Now, through the generosity of a happy local Whedonite with a large check, the show moves downtown to a larger ACT stage. Good sense will probably have you giving in to the bad doctor, too. STEVE WIECKING

Thursdays-Sundays, 8 p.m. Starts: Jan. 28. Continues through Feb. 12, 2011