UNDERCOVER

Being 'undercover' is disguising one's own identity or using an assumed identity for the purposes of gaining the trust of an individual or organization to learn secret information or to gain the trust of targeted individuals in order to gain information or evidence.
A separate technique is wearing 'plainclothes'. This method is used by police and intelligence agencies. To wear plainclothes is to wear "ordinary clothes", instead of wearing a uniform typically associated with the occupation, in order to avoid detection or identification as a member of law enforcement. Plainclothes police officers typically carry normal police equipment and identification. Police detectives are often assigned to wear plainclothes instead of the uniform typically worn by their peers.
Many countries allow the use of undercover law enforcement officers solely or primarily for the enforcement of laws against recreational use of certain drugs. M