In Gina Gionfriddo's comedy, a serial killer named Ed stalks the city, luring his victims by asking for help. To protect themselves, a group of New Yorkers form SAFE, "Stay Away From Ed." The first rule: don't help anyone. It's a matter of urban survival. U.S. Drag is the centerpiece of the sixth annual Summerworks festival of new plays presented by Clubbed Thumb. Pam MacKinnon directs.