Elephants Can Remember (S13E01)

Hercule Poirot delves into the chilling murder of an elderly psychiatrist, while author Ariadne Oliver is urged to dig into the mysteries surrounding two deaths from twenty years prior. As they pursue their individual inquiries, they discover a connection between the cases. Joining forces, Poirot and Oliver collaborate to unravel the enigma, piecing together the past to uncover the truth behind the intertwined tragedies.