Julka for the first time in her life feels happy. She has Olek - her one true friend and Aunt who is taking care of her while her parents are working abroad. When Aunt is falsely accused of stealing the only Monet’s painting in Poland and is arrested, Julka has to find the real thief. Normally she could count on Olek in such a situation but he seems to be even more distracted than usual, as he is trying to impress a newly met girl - Felka. Felka is the complete opposite of Julka – she is a happy 12 year old child from a loving family, a true optimist, and crazy a trouble maker. She can help with the investigation but Julka is afraid she will replace her in Olek’s life. The story about jealousy and trust is intertwined with a criminal mystery. Julka must learn that you can’t believe in a friend unless you first believe in yourself and a friendship put to the test may become even stronger.