The Quest Theatre Ensemble’s musical for kids retells the legend of young King Arthur, who was groomed by the magician Merlin for his noble, ultimately tragic destiny. Performed in the low-ceilinged, newly air-conditioned basement of a Catholic school, the low-budget show features imaginative oversize puppets and papier-mache masks, which will likely entertain (or scare) young children. Quest takes great pride in performing for free, “making art available to everyone.” But these good intentions are undermined by hammy performances, out-of-tune singing, excessive violence, clunky lyrics, and a libretto by writer-director Andrew Park that veers between goofy comedy and preachy pomposity. –Albert Williams a Through 8/19: Fri-Sat 8 PM, Sun 2 PM, Blue Theatre, Saint Gregory the Great Church, 1609 W. Gregory, 773-942-2227. F