The summary is:
Sorina is an adopted girl who loves swimming and idolizes Mariana, a Russian gold medalist. When Mariana comes to her school to recover from an injury, Sorina tries to befriend her but Mariana is rude and mean. Sorina suspects Mariana of cheating with pills and tries to expose her, but she is wrong and loses her place on the swim team and her brother Fred's trust. Fred is dating Mariana, who is actually hiding from some bad men in Russia. Sorina and Mariana fight and then make up, and Sorina gets her spot on the team back.
Here are some key facts extracted from the text:
1. Sorina is an adopted girl who was born in Romania and loves swimming.
2. Mariana is a Russian swimmer who won a gold medal and is Sorina's idol.
3. Sorina meets Mariana at her high school and they become rivals.
4. Mariana is dating Sorina's brother Fred, who is smart and clumsy.
5. Sorina finds out that Mariana is taking pills and accuses her of cheating.
6. Mariana reveals that she faked an injury to escape from some bad men in Russia and that the pills are vitamins.
7. Sorina and Mariana make peace and join the same swim team.