Frankie visits the registrar's office to solve the mysteries of her past, but she gets more than she bargained for when she takes a closer look at her parents' death certificates. Cat does her best to make sure she and Sam continue to enjoy their relationship's honeymoon period, a flirtatious encounter at work ends in disaster for Jay, and Tess gets a shock when she decides to pay Lou a surprise visit.

After moving into an up-market flat together, Tess explores the world of internet dating, and Frankie embarks on a self-destructive binge that lands her on the wrong side of the law. Meanwhile, Cat tries to make up for her lies by introducing Sam to her parents.

Tess's 30th birthday is approaching and she's desperate to ignore it, but her friends have other ideas. As Ed organises her surprise party his desire to tell her his true feelings reaches fever pitch, but could their friendship survive if Tess knew the truth? A work assignment brings Frankie and Cat closer together as they take a walk down memory lane, but as their feelings grow deeper a shocking revelation drives Cat back into Sam's arms.