It's Only Rock.

After watching a concert by a fledgling rock band, renowned songwriter Marczak decides to promote only its vocalist, Sylwia. The girl decides to leave her bandmates, including her boyfriend, Janek. She is to perform at a festival in Gradów. Marczak's ex-wife, singer Majka Lenczewska, whom he drove to a nervous breakdown, wants to return to the stage. Marczak asks Majka's current husband to compose a song for Sylwia. He agrees on the condition that the songwriter will not help Majka make her comeback.