Y/N never cared much about Harry Potter, but her best friend Ava is obsessed. During a movie marathon on a stormy night, the two girls are suddenly pulled into Harry Potter and the Half-Blood Prince and wake up as students at Hogwarts. With Ava determined to keep the story on track and Y/N just trying to survive it, they quickly discover that every choice they make changes the timeline. And the further they stray from the movie, the harder it becomes to find their way home.