The Adventures of Sherlock Holmes - The Adventure of the Copper Beeches
A young woman, Violet Hunter, visits Holmes because she received a peculiar job offer. She usually works as a governess and when she went into the agency, there was a man (Jephro Rucastle) there who told her she would be perfect for the job. He said she wouldn't have to take care of the child that much and that she would mainly be hired to do certain things (wear specific dresses, laugh at his jokes, sit by the window while reading a book). But most important, she has to cut her long hair.
Holmes forms a theory about the job but tells her to take it anyways. A few weeks after taking the job, she messages for them to go meet her. She tells them about the strange things that have happened while at this job. When she sits by the window reading, she is never allowed to look out the window. So when she brought a mirror to peek behind her, she saw a man there. The owners of the house asked her to wave him away. She never had to read by the window again after that. Another strange thing was that the dresses she had to wear fit her perfectly. And that in the bottom drawer of the wardrobe in her room, there was a braid that looked exactly like the one she had cut off before accepting the job.
But most peculiar of all, the way to the attic was locked and when looking from outside, one of the windows were clearly shuttered. She investigated before sending for Holmes and encountered a scary creature behind the shuttered room in the attic.
Result: Turns out the man outside(Mr. Fowler) was the betrothed of the family's daughter (Alice). They hired Miss Hunter who resembled Alice to convince Mr. Fowler to go away and that Alice no longer wished to see him. The night that Holmes arrived, Mr Fowler devised a plan to rescue Alice, with success. Miss Hunter later became the principal of an all girls school.