| | Hercule | Poirot | The famous Belgian detective. Hasting's close friend. |
| | David | MacAdam | The Prime Minister of England. |
| | Lord | Estair | The leader of the House of Commons. |
| | Bernard | Dodge | A member of the War Cabinet. |
| | Arthur | Hastings | Narrator. A police captain. |
| | Captain | Daniels | One of Mr. MacAdam's secretaries. |
| | Mrs. | Everard | Mr. MacAdam's aunt. |
| | Miss | Daniels | Mr. MacAdam's aunt. |
| | O'Murphy | | Mr. MacAdam's chauffeur. |
| | Detective | Barnes | A detective at Scotland Yard. |
| | Major | Norman | Detective Barnes's colleague. |
| | Japp | | Poirot's acquaintance. The Chief Inspector. |
| | Edith | | The little girl at the burglar's house. |
| | Captain | Lyall | The young pilot. |
| | John | Smith | The farmer of Clapham. |
