Janet breaks up with Denny because he told her he had to meet with his science teacher and then she saw him playing basketball. She becomes outspoken against liars, and she demands that the rest of the club sign a pledge to stop people from lying. They want the principal to make people wear a really ugly shirt if they get caught lying. Jessica doesn’t really want to sign it because she constantly tells lies, but she eventually gives into peer pressure.
Since it’s now the fifteenth summer break, the school is getting ready for a huge picnic celebration. A bunch of the Unicorns get dates, and Janet tells Lila and Jessica that since they don’t have dates, they have to spend the whole day with her. They make a bet that whoever gets a date first will get the day off, while the other has to hang around queen Janet.
Jessica is sure that Aaron will ask her, but he starts dragging his feet. She does beg her parents to give them extra money for a special picnic outfit, and they agree as long as she gets a B or higher on her math test. Unfortunately, she bombs the section on the metric unit, which brings her down to a C. The teacher tells her that if she walks his dog Sparky, takes a bunch of measurements and converts them to metric, he will raise her grade. She does it and runs into Denny who doesn’t seem too upset over his breakup.
Lila wants to impress Bruce and get a date for the picnic so she gets a perm. People start calling her names behind her back, but Jessica lies and tells her it looks good. After getting the money from her parents, she buys a new outfit and wears it to meet Aaron for ice cream. She runs into Bruce who asks her to the picnic because Lila looks so weird and she agrees. Then she runs into Aaron who also asks her to the dance and she says yes to him too.
Jessica tells Elizabeth what happened, and her twin gets pissed. They have a fight over lying and Elizabeth says that she never lies and storms off. Jessica makes a wish on a falling star that her twin would understand the importance of lying. The next day, Elizabeth feels the need to constantly tell the truth. She tells her mom that her food is dry, tells her teacher that he picked a boring topic for the upcoming essay contest, and tells the truth to everyone else. She tells Bruce that Jessica had two dates, tells Lila that people call her octopus head, and tells Aaron that Jessica made two dates and that she hates his shirt.
Lila screams and stops talking to her, Bruce breaks their date, and Aaron breaks up with her. She gets frustrated and makes another wish that her twin would cut it out. Suddenly, Elizabeth lies about everything. She thinks that the toast tastes delicious even though its days old, tells her teacher that she loves the essay but that their new puppy ate her rough draft, and acts like Jessica is the best sister in the world. She tells Lila that Jessica wants to be just like her and she tells Aaron that Jessica never had a date with Bruce though he did ask her.
While all this is going on, Jessica screws things up for Janet. She tells Denny that Janet is heartbroken over losing him, and she tells Janet that Denny was crying over her even though it was just allergies. He hangs out with her a little and meets Sparky who it turns out loves crumb cake from his favorite store. She schemes to get them back together, but Elizabeth almost ruins it by telling them the truth. Then she turns around and says that Jessica thinks of Janet like an older sister and was willing to sacrifice herself to get them back together.
Jessica makes another wish and Elizabeth goes back to normal. Lila shows up and takes her to a fancy spa for a makeover, only she has the guy give Jessica a perm and puts her hair back to normal. She does it because Elizabeth told her how much Jessica wanted to have the same look. While going home, she sees Sparky running around in the storm and tries to help him.
He runs into a garage and it’s Denny’s house. Denny tries to get the dog out from under his mom’s car, and the dog refuses to budge. They ride bikes over to the bakery and run into Janet who sees them and rushes off. They try to buy a cake, but she bought the last one. When they go outside, she gives them the cake, which has a note on top to Denny. She thought they were on a date, but he explains everything and they get back together.
They manage to help Sparky and get him home, but she gets back and her parents ground her for a month for sneaking out. The next day, they come home early and tell her that her teacher called them in for a conference and explained everything. Oh, and because of a mixup with his grading key, she really did get a B on her test after all. Then Elizabeth wins the essay contest by writing something about the trouble with lying.
*After all that talk about wearing something special, Jessica winds up wearing jean shorts and a white tee shirt to the picnic. Ooh, fancy.
*According to Elizabeth, the only time that she ever lies is when she needs to get Jessica out of trouble. How quickly she forgets every other book in this series!
*I think it’s funny that the Unicorns are so anti-lying when they constantly tell lies to each other.
*Jessica’s perm washes out because she spends the night running around in the rain, which I knew would happen because I saw Legally Blond LOL.
*Jessica gets grounded early on because she “lied” about getting a B on her test, which totally isn’t true. Doing extra credit work is no different than answering extra credit questions on a test.
*Elizabeth is one of the first people to get a date to the picnic. When Todd asks her, she thinks about how she wouldn’t go with anyone else. Yeah right.