There's a song where she owns being 31 and single, and so what? In 1960s Cambodia, that simply wasn't done. Pen Ran sang it anyway. Between psychedelic rock, cha-cha-cha and near-constant controversy, here's a look back at the meteoric career of a Cambodian singer whose disappearance under the Khmer Rouge remains, to this day, wrapped in unanswered questions.