'Harry Potter' author J.K. Rowling is writing a crime novel.The Scottish writer - who recently confessed she broke down in tears after finishing the seventh and final book 'Harry Potter and the Deathly Hallows - has been seen "scribbling away" on a detective plot in an Edinburgh cafe.Rowling is refusing to reveal the plot of her new tome, but said on her website: "I want to write something completely different. I can take my time. And the idea of just wandering off to a cafe with a notebook and writing and seeing where it takes me for a while is just bliss."She added: "I'll do what I did with 'Harry Potter' - I will write what I really want to write."Rowling wrote the boy wizard's first adventure, 'Harry Potter and the Philosopher's Stone', in an Edinburgh cafe when she was a struggling single mother.The magical tales of Harry and his Hogwarts pals have made Rowling one of the highest earning writers of all time, and one of the richest women in the world with an estimated fortune of £576 million, according to Forbes magazine's annual rich list.Earlier this year, Rowling revealed plans to write another 'Harry Potter' book.The 41-year-old writer said: "I might do an eighth book for charity - a kind of encyclopedia of the world, so that I could use all the extra material that's not in the books."