In Agatha Christie's detective story Peril at End House, was Mrs Croft really an invalid? Or did she just pretend to be one?
We find out in the ending of the novel that Mrs Croft was a criminal. She could get away with pretending, because she came recently from Australia, so nobody really knew her past history. Pretending to be an invalid could give her an easy alibi, and indeed that method was used in at least one other Christie story. However, the ending doesn't seem to reveal whether this was the case.