Murder Ahoy

Murder Ahoy is a movie starring Margaret Rutherford, Lionel Jeffries, and Charles 'Bud' Tingwell. After Miss Jane Marple is made a trustee of a merchant marine training vessel, a fellow trustee is poisoned, and ship's officers are...
During an annual board of trustees meeting, one of the trustees dies. Miss Marple thinks he’s been poisoned after finding a chemical on him. She sets off to investigate at the ship where he had just come from. The fourth and final film from the Miss Marple series starring Margaret Rutherford as the quirky amateur detective.