In the final episode of this series of Secret Diary of a Call Girl, Alex (Callum Blue) and Belle (Billie Piper) are trying to make their relationship work, but it’s not easy. Belle’s resolve is tested when Stephanie (Cherie Lunghi) turns up on her doorstep offering Belle one last job - an appointment with a mystery client who has asked specifically for her. Belle is tempted but refuses, she’s going straight.

However, Belle still can’t adjust to normal life and when Ben (Iddo Goldberg) suggests she tries writing about her experience she scoffs. Ben drags her to meet a publisher and Belle freaks out - she won’t be judged by society like this. Belle deeply misses the job, and ultimately she cannot help but give in to Stephanie to get her fix.

Bambi (Ashley Madekwe), a romantic at heart, tries to dissuade Belle from going through with it. But Belle can’t say no, and we see her enjoying the preparation for the client. This is what she missed – the buzz, the mystery, the rush. Belle walks into the hotel room and her mystery client turns around – it’s Alex. He couldn’t help but test her and Belle couldn’t help but give in to temptation. This shocking encounter leads to the ultimate breakdown in their relationship.

That night Belle sits down at the lap top again, and this time her story flows out of her. Fast forward and we see Belle in disguise being interviewed on TV, she is now a best-selling author – yet also an escort. After all a girl’s got to do her research.

Thursday, 23 October 2008, 10:00PM - 10:30PM, ITV2