The Central Intelligence Agency (CIA) -led operation is part of MKUltra, an illegal human experimentation program testing various drugs and practices for the purposes of "mind control."
Bugging equipment and two-way mirrors are installed in fake "bedrooms," where unsuspecting men are taken to their room by a sex worker, dosed with LSD, and then questioned by the sex workers while CIA agents watch what happens from the other side of the mirror. The sex workers are given some cash and an agreement that the CIA will help them get out of any future tangles with law enforcement.
Operation Midnight Climax leads to both the collection of data on LSD and to the creation of a range of programs aimed at using sex workers as part of the CIA's overall techniques.