In the novel The Floating Admiral, Célie Blanc was the maid of Elma Fitzgerald. She came to Rundel Croft with Elma, but left abruptly without waiting for her wages. According to Jennie Merton, Célie had told the other girls that the place was like a mortuary, although Jennie didn't know if she meant Rundel Croft or Whynmouth.
According to Mrs Emery, Célie spoke English beautifully, and was a nice enough person to speak to. However, Mrs Emery disliked that she seemed to be too intimate with Elma. She had seen looks pass between Elma and Célie which she felt ought not to pass between persons of different stations in life.
Célie made an appointment with Reverend Mount, as well as Elma, and Arthur Holland, regarding some information she had about Admiral Penistone's death. However, she was found dead at the Vicarage, having apparently committed suicide. It was revealed that not only had she been Elma's maid, she had also been Reverend Mount's wife, and the mother of his sons, Alec and Peter.
Célie had left her husband and children, and run away with another man. They had wanted to marry, but Reverend Mount could not reconcile it with his conscience to divorce her.
It was revealed that on the night of the murder of Admiral Penistone, Célie had called on Reverend Mount, and urged him to reconsider his decision about the divorce. it was also revealed that her lover was Walter Fitzgerald, Elma's brother.
Inspector Rudge suggested that when Célie arrived at the Vicarage on the night of Admiral Penistone's murder, Walter intercepted her in the garden and talked with her in the summer-house, and then rowed to Whynmouth with her, in the Vicarage boat.
Inspector Rudge also suggested that Célie was killed by the person who murdered Admiral Penistone, because she was going to tell Reverend Mount and the Hollands what she knew about the Admiral's death. The Inspector suggested that the murderer had made Célie hold the knife to her heart, and kept one hand over hers. The murderer later revealed that Célie's death had come about almost exactly as the Inspector had suggested, except that they had not intended to murder Célie. Célie had heard the Hollands in the next room, and had attempted to escape. The murderer tightened their grip on her, and so drove the knife in.