trojan horse ' one of the thieves was to hide inside .
the gang then planned to put real money in a briefcase and show it to a jeweller at a pre-arranged meeting , before placing it on the floor .
then , while a price was being agreed at a nearby table , the man in the cabinet would switch the case for one containing counterfeit notes .
but the three men and one teenager were seized when police swooped on a conference room at a hotel in manchester city centre .