Nancy and Bess are off on the most exciting vacation ever. Nah, I'm just messing with you. They're actually staying with a friend of Carson, Nancy's dad, and going to a music festival. Not something cool like Woodstock, but a symphony festival with a pianist competition. Thrills and chills, right?
The day after arriving, they decide that horseback riding seems fun and stop by the first stable they see. Conveniently, it's also Keiko and Ted, two of the three remaining competitors are riding. They meet up, Ted instantly falls for Ms. Drew, and they decide to go riding together.
While away from the pack, they hear a scream and rush to find Keiko laying on the ground and holding her arm. She tells them that she accidentally fell off her horse, and Ted agrees to rush and find a doctor. The doctor says she sprained her wrist but needs medical attention, so Ted takes her into town. Nancy find proof that someone placed burrs under the saddle to aggravate the horse and that someone deliberately cut through the saddle too. She even gets proof that someone brought those burrs with them because they aren't native to Massachusetts. Lucky bastards, those things hurt!
Turns out that Keiko's injury looked way worse than it really was and that she can compete that night again. This seems to upset both Maura and Jean-Claude, two of the other competitors. They were eliminated earlier, but both have a chance to come back if one of the other finalists can't perform. We also get to meet Andrew, the third finalist who keeps trying to get them to try some mushroom salad he made form mushrooms he foraged himself. No surprise, he winds up poisoned by the mushrooms. Since he claims he didn't pick poison mushrooms, Nancy becomes convinced that someone wanted to eliminate him after failing with Keiko.
That doesn't stop our little group from heading out on a sailboat with Ted though. Jean-Claude claims that he can barely swim and knows nothing about sailing, so he remains behind. While out on the water, another boat comes racing towards them and almost causes a huge crash. Jean-Claude was the one driving the boat and admits that he had more experience than he said but claims it was just an accident.
Nancy then hears that Maura got food poisoning at a competition in Europe the previous year. The finalists that year were her and Jean-Claude, and both Ted and Keiko were eliminated early. Maura is so busy practicing that she doesn't want to talk to him. Given that she's not in the competition, that's a little strange. Nancy heads over to Ted's room and finds that someone broke in right before she finds him laying on the ground with a head wound. He tells her that someone hit him over the head with a metronome before taking off.
Ted looks around and realizes the only thing missing are the scores he received from the judges. They give each pianist their scores, and the pianists then write down their own notes. He claims it's the most important thing to him and the only way he can better his performance. Nancy then hears that one of the judges suspiciously dropped out of the competition at the last minute.
After stopping by for a chat with her dad's friend, Mrs. Wheeler, she and Bess do a little shopping. They overhear someone talking about Grace Hammel, the new judge, and how it will make Ted happy. When they get closer, they discover Maura and her friend Abby. The two girls tell them that Craig Lucas, the judge who dropped out, was judging a competition where Ted finished last and that the younger pianist believed the judge had it out for him. Also, that Grace is close friends with Ted's teacher. Nancy later gets a phone call for the local police department telling her that Maura's fingerprints were on the metronome.
Since she doesn't really have proof of anything, Nancy and Bess head out to dinner with Mrs. Wheeler. She invites a special guest without telling the, Craig Lucas. Lucas seems reserved at dinner and changes the subject every time Nancy brings up the competition. His ears do pick up when he hears she's a detective though. After dinner, he tells her that the reason he dropped out is because someone blackmailed him!
He takes her up to his private office and shows her a note he got in the mail. Someone threatened to take one of his scores public if he didn't drop out. Lucas then tells her that his former teacher, some famous composer up there with Cole Porter, gave him three themes to use as he wished. He turned those themes into super popular songs that made him a fortune. Someone broke in, stole them, and then threatened him.
Before he can tell her more, there's a knock at the door. In steps his replacement, Grace Hammel. Grace just learned about the weird accidents and freaks out a little before basically leaving. There's really no point to her scene. Lucas asks Nancy to help him find out who blackmailed him and who keeps trying to hurt the competitors.
Nancy gets home in time to learn that Ted was just there and invited she and Bess to come to a nightclub with him. They change clothes and head out, but Nancy sees a hazard sign in the middle of the road, swerves to hit it, and almost crashes the car. Another car coming from the opposite direction stops and Alexander climbs out. He tells them that he came down that same road an hour before and the sign wasn't there. Nancy suspects it was Ted but still meets him at the club. I miss Ned.
Ted tells her that he didn't see the sign and suggests they dance instead of talk. He winds up kissing her on the lips, which seems to freak her out. Nancy runs to get a soda and sees Alexander at the club. Man, that guy moves fast. She also finds him sitting and chatting with Grace.
Our intrepid girl detective gets close enough to hear them talking about Ted and what sounds like Grace agreeing to vote for Alexander before the music gets too loud. She winds up back at their table to find that Bess talked with Maura and she has an alibi for all the events. Nancy then finds a drink at the table, which Bess assumes is one Ted brought for her. After drinking the glass, Nancy passes out in the middle of the dance floor.
When she wakes up, Ted wants to keep dancing and doesn't realize anything is wrong until she tells him what happened. She and Bess leave, and she's somehow fine the next morning. So fine that she wants to keep investigating. After going through Maura's room, she heads to Ted's room and finds the stolen score there. Someone grabs her from behind, and when she turns around, she finds Ted in front of her.
Cut to Nancy and Bess chilling and chatting about what happened. Ted heard rumors about Lucas, broke in, and stole the score before blackmailing him. He thought he could never win with Lucas as a judge. He also tried to eliminate the others because he thought that he would do better against Maura and Jean-Claude, and he poisoned Maura the year before because he just plain didn't like her.
They go to the competition and find out that Grace withdrew after Nancy told the panel what she overheard. She convinced Alexander that she would help him win if he agreed to become a teacher at his school. Maura thinks she has the competition in the bag, but when the results come in, Keiko actually wins. And now I know way too much about piano competitions!