'Belle de Jour' introduces herself to us, talking directly to camera,as she will throughout the series, and explaining that she is a call-girl, working through an agent - partly for safety reasons but also because she does not come cheap. Her real name is Hannah and her family believe that she is a legal secretary, which she told them as she imagined they would find it too boring to ask her about. She explains the need to keep her two lives separate, even to the fact that her apartment is split into two halves, depending upon who she is for which visitor. However, she does break the rules when entertaining a shy young man called Daniel, revealing her true name to give him encouragement. She is more professional with a favourite client called the 'horsey-man' whom she sits astride and hits with a riding crop.

At a prestigious party, Belle has to decide between dumping a smug, over-possessive client in favor of her dream date, but family matters intervene after she's made her choice, and her best friend gets a clue to her secret life.

Belle goes to a hotel room to have sex with Ash, who was her first ever client and for whom she has a soft spot. However Ash falls asleep, which allows Belle time to go downstairs and pick up another punter for a session in his room before returning in the early hours to Ash, who is blissfully unaware of what has happened.

Belle is taken aback when her accountant informs her that he is into punishment and would like to engage in a sado-masochistic scenario with himself as her slave. She is inexperienced and is put in touch with the domineering Madame Sirona, who turns up at Belle's flat with her 'slave', a scantily-clad, shaven-headed man, whom she humiliates to his satisfaction by way of demonstration. Before the accountant returns Belle meets her friend Ben, who tells her he is getting married. She is annoyed that he had not told her sooner, and further annoyed when he rings her as she is about to engage in her session with the accountant. In her anger she knocks him around more than she had intended and feels the need to apologize to him but he is perfectly satisfied, believing it to be part of her act.

Belle finds it difficult to share her favorite customer with Naomi, whom she has tried to befriend. Ben finds it difficult to accept the big revelation about his best friend,, and triggers her to reflect about how she got into The Life.

Belle gets a bad online review from a customer, and feeling down, accepts a midnight encounter which turns awry. Ben advises her to try her luck at a normal relationship, but has to bail her out when the guy overstays his welcome.

Belle is engaged by a couple who married very young and have been together for twenty years. To celebrate their anniversary they want to have sex with another couple but the brash young man Belle hires to make up the numbers lets her down and does not show. So Ben fills the breach and, despite his obvious feelings for Belle, is quite professional. However,Belle draws the line at their giving a repeat performance.

Seeking to promote herself, Belle has aspirations to become a courtesan, the high end of high class call girls, but being whisked off to Scotland by a powerful director turns out not at all what she hoped it to be, and she misses Ben.