It's just too easy to enter a theater, sit back and wait to be terrified, amazed, moved or entertained. Theater is a live medium that works best when audience members are involved and there's a genuine current between them and the actors. When you attend Shadow Theatre Company productions, you usually feel a distinct sense of ownership among the viewers. People sigh at sad moments and laugh generously at happy ones. When the youthful Quatis Tarkington, playing an elderly man and kneeling at his lover's feet, asked for help getting up, there was a sympathetic groan from parts of the audience. Best of all was the jovial response to Four Queens, No Trump. The play is centered on bid whist, and it was clear the audience knew the game. They cheered some moves, tut-tutted over others, even offered instruction. And though the actors didn't respond directly, you could tell all this empathy revved up their performances.