From the book jacket: "It wasn't the first time I'd been shut up in the closet, if closet isn't too grand a word for the little cupboard under the stairs." So begins the diary of Mary, a Victorian maid-of-all-work in the employ of one Dr. Jekyll.
Mary Reilly has escaped the dark back streets of her childhood, the brutality of her father, and the indifference of her teachers with two unusual advantages: she is observant and she is literate. It is not surprising that she soon attracts the notice of her employer, the well-known philanthropist and scientist Dr. Henry Jekyll. Mary returns his interest with an obsessive devotion born of her conviction that as a gentleman, he can have no connection to the long nightmare that was her childhood.
But even as Jekyll's confidence in Mary's intelligence and discretion grows, her conviction is put to the test. Her master relies on her to keep secrets she does not wish to know and sends her on errands that recast the black terror of her childhood in bloody relief. Daily she records in her diaries her conversations with her gentle Master. She describes his strange illness which weakens him to the point of bedridden exhaustion, his preoccupation with his "scientific investigations," and finally his decision to take on as his assistant a brutal young man of questionable origins and intentions, Mr. Edward Hyde. Gradually, Mary finds herself not only the keeper of her Master's house but the guardian of his crumbling sanity and the only one in possession of the dark knowledge that might save his life.