Curtain: Poirot's Last Case (Hercule Poirot Series) by Agatha Christie

A wheelchair-bound Poirot returns to Styles, the venue of his first investigation, where he knows another murder is going to take place...

The house guests at Styles seemed perfectly pleasant to Captain Hastings; there was his own daughter Judith, an inoffensive ornithologist called Norton, dashing Mr Allerton, brittle Miss Cole, Doctor Franklin and his fragile wife Barbara , Nurse Craven, Colonel Luttrell and his charming wife, Daisy, and the charismatic Boyd-Carrington.

So Hastings was shocked to learn from Hercule Poirot's declaration that one of them was a five-times murderer. True, the ageing detective was crippled with arthritis, but had his deductive instincts finally deserted him?...