"Keeping It in the Family" is the 131st episode of Casualty and the third episode of the 9th series. It was preceded by "First Impressions" and followed by "Chasing the Dragon". The episode was directed by David Innes Edwards and written by Keith Temple.
An office worker is brought in after taking a tumble at work. She is eager to get back since her husband is unemployed. She eventually admits to Kate that she fell because her employer, who is married to her sister, was sexually harassing her. She decides to reveal the truth and resign. Mike is snappy with the staff and admits to Charlie his wife has left him; Kate also realises the truth. A middle-aged couple are at a supermarket when the woman has her bag snatched; the man chases after the thieves but collapses. He has hid the fact he has angina from her and dies in hospital. Ash learns the couple were not husband and wife but brother and sister in an incestuous relationship. A woman named Marian is brought in after shutting her hand in a skirting board. Josh and the police find an elderly woman stabbed to death and her daughter Ruth stabbed and injured. Rachel notices a photo of Ruth in Marian's bag but Marian beats her before fleeing. Charlie and Mike stop her throwing herself out a window; Ruth is her sister and she and her mother moved into Marian's house, drove her husband away and constantly bullied and belittled her until she snapped.