Sad Cypress (S09E02)

Elinor Carlisle, a young woman set to wed the charming Roddy Winter, becomes embroiled in a scandal when she is accused of murdering her romantic rival, Mary Gerrard, through poison. With the odds stacked against her, Elinor turns to Poirot for help. Despite the substantial evidence suggesting her guilt, Poirot is determined to uncover the truth and clear her name.