The world of covert surveillance is being investigated by BBC News Online.
Bugging and eavesdropping can form a key part of police investigations and intelligence gathering by the security services.
To find out how it is done follow our two operatives into the hotel room of a key suspect. They have gained access and are now planting bugs in well chosen locations.
To find out where they have placed them click on the link above and search the room with your mouse.