Its Halloween and farrier Lucas Shoemaker is working in his stable when a ghostly horseman, riding a flame-spitting horse, tramples him to death. At the Pie Hole Chuck is putting up Halloween decorations, despite Olive's insistence that Ned hates Halloween with a passion. With Olive still delivering Chucks homeopathic baked pies, Chuck wants to know what Olive has actually told her Aunts about her. Olive still assumes that Chuck has simply faked her death, and Chuck is relieved that she doesnt suspect what really happened. Ned comes in and is taken aback by the Halloween decorations. Olive plays coy about exactly what she has told, before hearing about the death of Lucas Shoemaker. Olive immediately goes to her safe deposit box and takes out the money to hire Emerson to investigate Shoemakers death, believing he was murdered. It turns out Olive used to be a jockey and competed against the murdered man. Emerson takes the case and goes to the morgue with Ned and Chuck. They interrogate the toothless Shoemaker who says that John Joseph Jacobs had killed him - despite Jacobs dying seven years ago. When they let Olive know she gives them a list of other jockeys who might also be in danger. Olive is worried about identifying Jacobs and promptly faints. Emerson goes to check out a local jockeys bar while Ned goes alone to the stable to look for clues and talks Emerson into taking Chuck with him. Olive wakes up and tells them that Jacobs was the golden boy of racing until he competed in the Jock-Off 2000 and fell off his horse. Olive, the winner, and the other jockeys inadvertently trampled him to death. Emerson figures that someone is trying to avenge Jacobs. Olive figures that someone is going after the people who took part in the race, in the order they finished in. At the jockey bar Emerson talks to the bartender, Pinky McCoy, while another jockey warns about Jacobs ghost and that Jacobs tomb has been broken open. Olive and Emerson go there and open the coffin but all they find inside is the skeleton of a horse with no legs. Chuck and dog Digby go to the stable and find cracker crumbs before Emerson surprises them. Chuck, Emerson, and Olive go to see Jacobs mother, Mamma Jacobs. She invites them in and says that she made peace with her sons death. She shows them his ashes, explaining that she had his horse All the Gold secretly buried in Jacobs tomb. Theyre unaware that someone is watching them through the heating vent. At Pinkys bar, the ghostly horseman appears again and tramples him to death. Meanwhile, Ned goes to visit Chucks aunts and asks them to tell him what they can about his father. Ned realises that the pie they served him is from the Pie Hole as the strawberries die when they touch his tongue and goes to leave as Vivian tries to console him.
Ned joins everyone else at Pinkys Bar where they are checking out Pinkys corpse and finding cracker crumbs on the floor. Chuck gets Olive out of the room while Ned and Emerson interrogate Pinkys corpse. Pinky reveals he fixed races and asks them to apologise to Olive - he figures Jacobs is seeking revenge on him and Olive benefitted. Olive explains that Jacobs girth had been cut by one of the other jockeys, causing him to fall to his death. The jockeys agreed to keep the secret and burn the saddle, despite Olives objections.
Ned and Emerson go to find Gordon, the last jockey, while Chuck guards Olive at her apartment. Olive goes to get some alcohol in her bedroom but sees a horseshoe outside her window. She climbs up to the roof and sees John Joseph Jacobs. Chuck knocks him out and they notice hes two feet taller then he should be. Jacobs comes round and explains that he survived the fall but his legs were badly broken, so they transplanted his horses legs onto him. He has been living in his mothers basement while he relearned how to walk. Olive tells him to get out and live and Jacobs agrees.
The three of them go to Mamma Jacobs house and the women realise that Jacobs, being diabetic often eats crackers. They examine Jacobs supposed ashes and realize theyre from the burned saddle. Suddenly the horseman rides into the house. Emerson and Ned discover that Shoemaker had confessed everything to Mamma Jacobs and gave her the ashes to prove what he was saying was true.
The horseman removes the mask to reveal that its actually Mamma Jacobs seeking revenge for the fact her son's career was so unfairly stopped short. They run out of the house as Mamma Jacobs gallops after them. Ned and Emerson get to the house and hear Chuck and Olive in the woods. As they are chased by Mamma Jacobs, Chuck twists her ankle but Olive gets her to safety before Mamma Jacobs tramples her. Ned grabs her just in time while Emerson hits Mamma Jacobs with a shovel. Olive kisses Ned, who drops her immediately to go to Chuck.
Mamma Jacobs ends up in jail while Olive gives the trophy cup and winnings to Jacobs. Ned and Chuck go to her aunts house and Ned says he knows about the pies she been baking for her Aunts. Chuck finally gets to see her aunts, but only dressed up as a ghost for trick-or-treats.