Hoofbeats of Danger is the second History Mystery.
- Annie Dawson-The main character. Annie is an adventurous and dreamy girl who loves living at the Red Buttes station where daring pony express riders come from coast to coast. More importantly she loves her pony, Magpie. (born in 1849)
- Davy Dawson-Annie's six-year-old brother who admires Billy Cody.
- 'Ma' Dawson-Annie's patient, but firm mother
- 'Pa' Dawson-Annie's silent and stern father
- Billy Cody-An easygoing and adventurous young rider who loves to brag about his adventures in the Pony Express.
- Jeremiah-A tall man who is the stablehand at the Red Buttes Station.
- Magpie-Annie's favorite horse who is owned by the Overland Express Company
- Redbird Wilson-A girl who is part Shoshone Indian and is Annie Dawson's good friend.
- Nate Slocum-One of the best stagecoach drivers at the Overland Express.
- Chester Ambrose-The Stagecoach Guard
- Horace-The Drover
Chapter One: The Mail Must Go Through
Annie is looking at the clouds and Annie thinks how they'll go past the east of the Mississippi river before rain drops. Annie recalls how her parents crossed the river on the way to California when she was a baby. She tells herself that she'll one day see what lies east of the river. She then hears a distant rumble. She asks her younger brother, Davy, if he heard that. Davy looks up from his book and asks what she heard. Annie says she hears hoof beats, meaning that Billy was coming. She runs up to her house where the other Pony Express rider, Tom Ward, brings out his horse. Billy Cody comes riding in on Annie's favorite horse, Magpie. Billy unhitched the mochila and tossed it over to Tom. Tom put the mochila on his horse, and then tells Billy he'll see him in a week as he rides off. Billy gets off Magpie as Annie takes over the reins. She tells Magpie she missed her and Billy teases Annie not to spoil Magpie as she's a working horse. Annie offers to groom and feed the horse in Billy's place. Davy comes up to see Billy, and he starts to tell the two about his journey here. Billy tells an exciting story, saying that he ran into an Indian buffalo hunting party who tried to shoot arrows at him. Mrs. Dawson interrupts his story, telling him to wash up if he wanted to wear his clean shirt. She tells Annie to fetch some water from the river when she's done taking care of Magpie. As she leaves, Billy mentions he'll pick a nosegay for Annie's mother, to keep her on her good side. Annie brings Magpie into the stable and she begins to think about how her dad's knowledge of being a blacksmith that he learnt in the California gold-mining camps helped him get his current job as a stationmaster. Mr. Dawson sees Annie and Magpie walking by when he demands to Annie "What's wrong with that horse?"
Chapter Two: Watching and Worrying
Annie freezes up. She asks her father what he means, and he asks her if she can't see that Magpie is favoring her left hind foot. He picks up the horse's leg and grunts that she has a loose shoe. He asks Annie who rode the horse. Annie answers "Bill Cody" in a small voice and when asked where he was, she only gestures to the hay meadow. As her father heads to the meadow calling Cody's name, Annie can't help but feel somehow responsible fore getting Billy in trouble. She thinks how whenever something around the station went wrong, her father would overreact. She thinks how she sees her father be so gentle with animals and wonders why he didn't realize the same manner worked with people as well. Annie brings in Magpie into the stable and starts unsaddling the horse when she hears loud voices entering the station yard. Her father is asking Bill Cody angrily how can he believe him, pointing out this wasn't the first time he had been careless with the horses. Bill Cody tries to protest, saying that she was fine when he came in, but Mr. Dawson cuts him off. He tells Bill that it's up to the horses to deliver the mail as soon as possible and the riders are just extra weight. Annie starts to tear up, knowing exactly how Billy must be feeling. She wanted to please him, but when her father would get anxious, she would become tense, clumsy, and forgetful. Mr. Dawson comes in and asks Annie if she's done with Magpie. He tells her to bring her to the forge and as she began to walk away, Annie tried to defend Billy, saying that she saw Magpie pawing at some rocks in the yard. Her Pa grumbles that riders just want to be adventure heroes and they have no responsibility. Annie almost blurted out he was being unfair, but she knew it was useless to quarrel with her pa when he was worried about the station. He checks on Magpie's hoof and admits that it doesn't look injured. He wants to take precautions, and asks Annie to get some salve from the remedy cabinet. She grabs the medicine and walks to the forger where her ma is talking to her pa. Mrs. Dawson tells him she overheard him and asks what did Billy do. As Annie hands her father the salve, he mutters that he misused a horse. Annie realizes with surprise that her Pa seemed embarrassed about his outburst. Her mother assures him that the animal is all right now and that although Billy can be careless, he didn't mean any harm. Mr. Dawson begins to make a new horse shoe and tells his wife that he can't let things slack and doesn't want to lose his job. His wife assures him he won't lose it, but he remains worried. He tells how the Overland Express is having money troubles because the Butterfield company is trying to run them out. The two companies are fighting over who will get the government's mail contract and Pa tells that when the bosses start to get edgy, they crack down on the station masters. Annie becomes worried; she doesn't want to go back to the mining camps back in California. She enjoyed life at the station much more, and if she left, then she would have to leave Magpie. Mr. Dawson puts on the new horseshoe on Magpie and Annie brings her back to the barn. She brushes the horse and admires her coat. She hears a wagon rumble into the yard and goes out to see the station's stablehand Jeremiah. When Annie asks if he had finished harvesting the meadow, he simply nodded. He gives Annie some hay and guesses that Magpie's arrived. Annie grins and confirms his guess. She tosses the hay into Magpie's stable and tells the horse "Only the best for you, girl."