Gemma Foster, a doctor at the Parminster Medical Centre, is happily married to property developer Simon with a young son, Tom. Then one day she finds a blonde hair on Simon's scarf and suspects him of infidelity. Rather than confront him she confides in colleague Ros with his assistant Becky topping her list of candidates. At work she is at odds with elderly doctor Jack Reynolds, whose lack of professionalism renders him due for retirement whilst she also frees young Carly, a girl she has employed to follow her husband, from the influence of a drug-dealing boyfriend. However she is no closer to discovering the other woman's identity at Simon's fortieth birthday party. Written by don @ minifie-1

Annoyed to learn that best friend Ros knew of Simon having an a affair Gemma establishes the identity of the other woman, a patient of hers admitting to being pregnant by a married boyfriend and seeking a termination. Repairing to a bar Gemma meets patient Anwar, a married lawyer keeping the fact that he has a brain tumour from his family. Encouraged by Jack Reynolds Gemma confronts Simon but he denies having an affair. However his ailing mother Helen, whose own husband cheated on her, tells Gemma otherwise, leading to Gemma making an appointment with divorce specialist Anwar. Written by don @ minifie-1

On Anwar's advice Gemma acts towards Simon as if everything is as normal whilst using Carly to befriend her suspect for further evidence and Ros to quiz Simon - both with a negative result. She also involves married accountant Neil in establishing Simon's financial position, the relationship extending to the physical, though Neil does discover fraudulent anomalies on Simon's part involving the likely loss of the Fosters' home. However Gemma and Simon temporarily unite in grief following a family tragedy. Written by don @ minifie-1

To Ros's surprise Gemma agrees to reconcile with Simon, enjoying sex with him but faces another problem when an anonymous Internet troll posts harmful remarks about her work as a doctor - including the suggestion that she killed her mother-in-law. As a result she agrees to a voluntary suspension, whilst confronting the believed author. Simon is extremely supportive though still over-friendly with the woman Gemma believes is his lover. She goes to stay with the self-exiled Jack Reynolds before returning home to present Simon with an awkward shock. Written by don @ minifie-1

Gemma contrives to embarrass her rival at an awkward dinner party with the woman's family - where she exposes Simon's infidelity and his financial chicanery before moving on to exert revenge on her online detractor, though this time she does not succeed. Satisfied that she has broken Simon and alienated their son from him her obsession with vengeance gets out of hand, leading to a violent confrontation before matters are resolved. Written by don @ minifie-1