The mystery is okay, but ghostly superstitions aren't necessary to make a good mystery.
Felicity Merriman is the gentlewoman of the house for two weeks. Her horse, Penny, enters a race; her father receives lovely heirlooms with a curious history. It figures that this has to be the time for strange and creepy events.
Regardless of occasional carelessness, Felicity is a responsible girl. She owns up to her mistakes, no matter how embarrassing they are. She is quick to be a friend and is concerned for a girl suspected of being mistreated, as are her friend Elizabeth and Ben the apprentice. Mr. Merriman is a gracious gentleman.
It is suspected that someone is forced to steal.
As stated in the title, a ghost is part of the story. Felicity wavers between believing in ghosts and not (a tingling feeling in her fingers when she touches the heirlooms doesn't help). She and Elizabeth visit the reverend at the church and he tells them that he has an "open mind" on the matter of ghosts (he does not deny that they may exist). (Felicity later follows this thought.) He also briefly mentions the Trinity.
Felicity wears her coral necklace for good luck.
Mr. Merriman says to trust someone's recovery to God's will.
A girl has bruises on her arm, perhaps from beatings. Someone intentionally puts burrs under Penny's blanket and saddle. Felicity fears that she may be jumped and robbed when she feels she is being followed.
Drug and Alcohol Content
Felicity, Ben, and another boy cross the street to avoid two men ready to come to blows outside a tavern.
Crude or Profane Language or Content
This is more "unadvised/negative behavior": Ben and some other men place bets on horses at a race (and the effects are seen).
As the issue of ghosts isn't truly resolved at any point in the story, the mystery has some interesting "thoughts". It is advised that a real perspective of ghosts be provided; this may also open opportunity to talk about how imagination can get the better of us. Ghost aside, it's a fine story.