Monsieur Lecoq (leh-KOHK), a brilliant detective and master of disguise. He clears Prosper chiefly to shame Gypsy, who was formerly his mistress.
Prosper Bertomy (prohs-PEHR behr-toh-MEE), a trusted bank clerk who has one of the two bank keys and is therefore suspected of a robbery there. After being cleared, he marries Madeleine.
M. André Fauvel
M. André Fauvel (ahn-DRAY foh-VEHL), a Paris banker who possesses the other key to his bank.
Valentine (vah-lahn-TEEN), Fauvel’s wife. As a young woman, she had an affair with a young neighbor, Gaston de Clameran, and secretly bore a son in England. The child is now dead. Her husband is unaware of her indiscretion.
Louis de Clameran
Louis de Clameran (lwee deh klah-meh-RAHN), Gaston’s younger brother. He coaches Raoul to impersonate Valentine’s dead son. He goes mad in prison.
Raoul de Lagors
Raoul de Lagors (rah-EWL deh lah-GOHR), an impostor claiming to be Valentine’s son and now living with her as her “nephew.” He forces her to provide Fauvel’s key. Lecoq unmasks him by means of a scratch on the bank safe.
Madeleine (mahd-LEHN), Fauvel’s niece, who is in love with Prosper but is willing to marry Louis de Clameran in order to silence him about Valentine’s indiscretion.
Chocareille (shoh-kah-REE-yeh), called Gypsy, an ex-criminal and now the mistress of Prosper.
Fanferlot (fahn-fehr-LOH), a detective secretly married to Mme Alexandre.
Mme Alexandre (ah-lehk-SAHNDR), the manager of the Archangel Hotel, where Gypsy is hidden.
Cavaillon (kah-vay-YOHN), a friend of Prosper who carries Prosper’s warning note that puts the police on Gypsy’s trail.