Patrick Marber’s play can be a searing portrait of four needy adults who put passion before truth and loyalty. Two couples’ stories crisscross and bleed together as weak Dan betrays young Alice in favor of reserved Anna, who in turn is cheating on disgruntled Larry. Marber presents their intertwined fates with sharp, sparkling wit and offers some startling, even brutal observations on human nature. But Signal Ensemble Theatre’s treatment can be plodding. Director Ronan Marra’s use of overlapping spaces underlines the characters’ shifting loyalties too bluntly. And while the acting is good, it’s seldom great, so the foursome’s rages and betrayals lack intensity. –Jenn Goddu a Through 12/17: Thu-Sat 8 PM, Sun 3 PM, Wed 12/6, 8 PM, Chopin Theatre, 1543 W. Division, 773-347-1350, $10-$15.