The wannabe spies hone their skills at 'going grey' - the art of mingling in a crowd without being noticed. The trainers instruct them in using effective body language and building an instant rapport with strangers. The recruits then embark on their toughest mission yet, which will test their skills of persuasion, nerve and the ability to think on their feet. They attempt to gain access to an office building (during working hours) and take photographs of confidential documents without getting caught.