River Heights must be like one of the top cities in the world or something. The last book had the big Olympic type event and this one hosts an international chess tournament. Even though most players stay in the same hotel downtown, Donna, one of the top players, is staying at the Drew house with her twin sister Danitra. Their father is close friends with Carson and when he and his wife couldn't fly out, Carson offered to look after them.
Donna's biggest competitor is Greta, a young woman from Germany. Her sister, Anna, is already in River Heights as an exchange student, but her brother, Eric, and trainer, Esther, come with her. Esther approaches Donna and tells her to play up the rivalry between the two because it will make the tournament more exciting. Donna puts out that she just wants to play. She also shows Nancy this super fancy chess set she has, which belonged to her grandfather.
During the first tournament, we also meet some other people. Donna's coach Stricker comes around and whines about how she needs to play better without actually doing anything. He also demands that Nancy give Donna the quietest place in her house to practice. Eric also comes around a few times to complain about how he never wants to go back home. That makes Greta feel bad because she's homesick and really misses their parents.
Before the first game, someone breaks into the Drew house and steals some of the pieces from her chess set. They leave behind a note stabbed through the case with a knife that says to lose the first game or else. Donna ignores the note, plays her best, and wins. The person then sends a bouquet of flowers to the house with some of her pieces inside and another threatening note. Since this is a Nancy Drew book, we must get one scene of her brakes failing out and a mechanic telling her that someone deliberately cut the brake line.
It turns out that Greta got some threatening notes too. The notes seem to play the two women off each other, as if someone wants to build up their rivalry. River Heights also built a massive chess set with pieces that costumed players move. Someone rushes out of nowhere, knocks over a bunch of pieces, and tries to run away. When caught, he says that someone paid him to do it but that he didn't get a name.
Greta grows close to Bess because Bess is close to Anna or something. Bess comes to Nancy and tells her that someone kidnapped Anna. They left behind a note that told Greta she would never see her sister again unless she won the tournament. Eric flips out that she keeps telling people and points out that the note said not to tell anyone or they would kill Anna.
Nancy thinks Esther, Greta's coach, is behind everything. She sneaks into the woman's hotel room and finds a German magazine that has letters cut out, letters that match those used in the note Greta got. Nancy also hears Esther talking to someone about how Greta will win the tournament and how she has a plan in place to make it happen. Esther very nearly catches Nancy coming out of her room.
Greta almost breaks down during a match and concedes. Lucky for her, this is a double elimination tournament, so she has one more chance. Her and Donna get into it in front of a lot of people, with both girls shouting about how she is a better player. Greta wins her match and gets back in the tournament, and it somehow all comes down to the two of them.
Right before the match starts, Donna gets a note that someone kidnapped her twin sister and that unless she loses, she'll never see her sister again. Nancy starts putting all the pieces together and heads over to the house where Anna was staying. The woman of the house tells her that Anna went to the hotel to stay with her brother and sister while they were in town.
Nancy immediately rushes over and bangs on the door to the room number the woman gave her. Anna answers but pretends she's someone else until Nancy threatens to break the door down. She finally answers and confesses the whole thing. Eric hates Germany and never wants to go back. He made a bunch of deals in Greta's name to make money, but she has to win the tournament before he gets any of that cash. Anna agreed to work with him but didn't think he would take things that far.
After calling the cops, Nancy finds that Eric left his hat behind, sees a woman with a beagle, and demands that she let her borrow the dog. The woman refuses until the mother flipping Chief of Police tells her that it's a police matter. Nancy uses the dog to track Eric's scent and finds him hanging out in a storage closet with Danitra. The cops show up to arrest him while Nancy and Danitra run to the match.
Since Danitra and Donna conveniently know American Sign Language, they talk with each other. Danitra tells her twin that she's fine and everyone is safe. Donna comes back from certain defeat to win the game, and Nancy has to explain to poor Greta what happened. Donna then thinks that maybe it's time to give up chess and take up a new hobby.
*Nancy points out this girl Emily, who is the youngest player in the tournament. They talk about her for almost an entire page, which made me think she had an important role in the book. Nope. She literally gets one other mention later.
*Bess is so rarely in this book that when Nancy mentions Anna at the end, she asks what happened and why they were looking for her.
*There's a B-plot about a coach from Emerson College who wants to give Donna a full scholarship to run for the team. He keeps popping up and trying to convince her that she should give up chess to run. The coach even comes back at the end of the book to try one last time. There's really no mention of why he thinks she's a good runner though. If she's on the track team in high school, how does she have time to focus so much on chess?
*Nancy and Donna accidentally wander into a modeling show when trying to find the tournament. The head organizer refuses to believe that someone as gorgeous as Nancy isn't a model and offers her cash to model for him. Gag me.