When Christopher Shinn's Dying City — a difficult and sobering triangle among the widow of an Iraq War veteran, the dead soldier himself, and the soldier's identical twin brother — debuted at Mosaic Theatre last spring, audiences and critics were divided over the source material. It wasn't exactly a fun, joyous night at the theater, and some found the material heavy-handed. But there was something of a consensus when it came to the production itself, which artistic director Richard Jay Simon handled with tenderness, sensitivity, and palm-sweating intensity. Erin Joy Schmidt and Ricky Waugh both spelunked their characters to previously unseen dramatic depths, and Mosaic's technical team created authentic ambiance all around the elegant set.