| Hamilton Cleek, the Man of Forty Faces, and once known to the police as "The Vanishing Cracksman." |
| Superintendent Narkom, of Scotland Yard. |
| Lennard, his chauffeur. |
| Hammond } Detective Sergeants. |
| Petrie } |
| Constable Roberts, Police Officer at Hampton Village. |
| Dollops, Cleek's trusted friend and protégé. |
| Lady Margaret Cheyne, the only and orphan daughter of |
| Lord Cheyne, whose title became extinct on his death, some years previous, but by his will he has left her all the family jewels, including the ill-fated |
| Purple Emperor, a big violet-coloured diamond looted from an Indian temple, and set as a pendant. She comes of age at 18, until when she is left in the charge of his eccentric sister, |
| The Honourable Miss Cheyne, a recluse, living in a lonely house, Cheyne Court, on the banks of the Thames. She has kept her niece at the convent of Notre Dame in Paris, since her childhood. Disappointed in love herself, Miss Cheyne has decided that her niece shall be a spinster also, but Lady Margaret has contrived to meet and fall in love with |
| Sir Edgar Brenton, the son of the man who jilted the Honourable Miss Cheyne, and whose chance visit to Paris with his mother, a year earlier, led to his acquaintanceship with Lady Margaret, and with whom he is deeply in love. Unfortunately he is also loved by |
| Jennifer Wynne, the orphan daughter of a doctor who lived in Hampton previous to the present one. She earns a living by teaching, and lives with her brother, |
| Bobby Wynne, a young spendthrift and gambler, in the power of |
| James Blake, the head of the Pentacle Club. |
| Doctor Verrall, the village doctor, loves Miss Wynne. |
