The musical version of the 1989 black comedy Heathers offsets its dark—and deadly—plot with sprightly, witty songs. Barrett Wilbert Weed, as tortured teen Veronica, gets to show off her rock bona fides on the anxiety-tinged “Dead Girl Walking” and the grandly romantic duet “Seventeen,” while ensemble pieces like the absurdly elegiac “The Me Inside of Me” and the debauched “Big Fun” revel in the dark humor that comes not only from Westerburg High’s increasing body count, but also from the more horrific moments of adolescence.