Luang Sawat (2012)

Detective Petch receives an assignment of investigating a murder case. The only evidence he has is a recording of a woman moaning while having sex. There are 3 suspects; May, a prostitute, Daeng, a hairdresser and Ploy, his own wife. He must have sex with all 3 women in order to find out who’s the owner of the voice in the recording. But the truth turns out to be not what he expected.