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.
| Actor | Role |
|---|---|
 Margaret RutherfordMiss Jane Marple | Miss Jane Marple |
 Lionel JeffriesCaptain Rhumstone | Captain Rhumstone |
 Stringer DavisJim Stringer | Jim Stringer |
 Charles TingwellInspector Craddock | Inspector Craddock |
 William MervynBreeze-Connington | Breeze-Connington |
 Henry OscarLord Rudkin | Lord Rudkin |
 Joan BenhamAlice Fanbraid | Alice Fanbraid |
 Nicholas ParsonsDr. Crump | Dr. Crump |
| MMiles MallesonBishop | Bishop |
 Derek NimmoSub-Lt. Eric Humbert | Sub-Lt. Eric Humbert |
 Gerald CrossBrewer | Brewer |
| NNorma FosterAsst. Matron Shirley Boston | Asst. Matron Shirley Boston |
 Terence EdmondSgt. Bacon | Sgt. Bacon |
 Francis MatthewsLt. Compton | Lt. Compton |
 Lucy GriffithsMillie | Millie |
| BBernard AdamsDusty Miller | Dusty Miller |
| EEdna PetrieMiss Pringle | Miss Pringle |
 Roy HolderPetty Officer Lamb | Petty Officer Lamb |
 Tony QuinnTramp | Tramp |