Complex sentence: Realizing that she had inadvertently caused Simón's death by accidentally blocking the door to the underground room while he was inside it, trapping him inside, Laura begs to be with Simón again and the children's spirits appear, with Simón returning to life.
Split into simpler sentences: Realizing that she had inadvertently caused Simón's death by accidentally blocking the door to the underground room while he was inside it, trapping him inside. She begs to be with Simón again and the children's spirits appear, with Simón returning to life.