Lancaster Castle was used as a prison until 2011. It was also a place where three suspicious deaths took place in the early part of the 20th century.
Between January and August 1911. Three members of the Bingham family, father William, son James and daughter Margaret all suddenly died. William Bingham had been the resident caretaker at Lancaster Castle. His son James had taken over the role after his father's death.
In the case of James Bingham, the Doctor suspected arsenic poisoning. Later it seems the other two might have also died of arsenic poisoning.
Suspicion fell on Edith Bingham. She was the housekeeper, having taken on the role after the death of her sister Margaret. Only Edith was not apparently a good housekeeper. She might also had been a fantasist. She seems to spend lavishly on her boyfriend, a budding filmmaker.
I thought despite the slant the drama took. It was all very sketchy and circumstantial.
In reality the jury took 20 minutes to decide a not guilty verdict. If Edith decided to get rid off her family, she would only make herself homeless.