Panic in the Reed's manor

Music Recommendation: Time Bubble - From Freaks - Tim Wynn

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Blood drained from Louise's face, her hands turning cold on seeing the fourth person in the portrait of the family painting. This was not possible, she thought in her mind. 

Emily, the maid who had been working in the manor, was the fourth wife of Graham?

Louise stared at the maid, who had an innocent-looking face in the painting. She had known and spoken to the girl since she had joined Reed's family in this manor.

She had spoken to the girl this very morning, and she was in living and breathing form.  So how could she be the fourth mistress?

Was there another wife after the fourth one, which no one knew about and was dead? But at the same time, Emily had never mentioned a word about being Graham's wife. Was her memory erased or suppressed like the rest of them?