Complex sentence: Yevgraf believes a young woman working on a dam project, Tonya Komarovskaya (Rita Tushingham) may be his niece, and tells her the story of her father's life.
Split into simpler sentences: Yevgraf believes a young woman named Tonya Komarovskaya (Rita Tushingham) working on a dam project may be his niece. Yevgraf tells Tanya the story of her father's life.