A market research institute has just been given a new commission to conduct research on extra-marital sex. Secretary Elvira Schlecker is calling up the researchers, while her favourite colleague, is as usual having sex with someone. We observe Klaus third interviewee telling about a foursome with three girls and his wife Jane. Klaus hires Jane on the spot as his new assistant. For the second investigative topic, prostitution, Klaus and Jane visit a brothel to observe whores talking to their clients. One of them shows them a one-way mirror, where they can observe her and one of her colleagues in the act. The final investigation is about masturbation, two girls Klaus is interviewing at a bus stop admit to practising it. However, on the bus they demonstrate that they have no difficulty pulling, and proceed to pull a fellow passenger's todger out of his trousers for a good licking. Subsequently everone is heading for the next Bierkeller where an orgy quickly ensues