Books on screen

Basil of Baker Street/The Great Mouse Detective

These days, both this book and the movie are pretty obscure. In spite of reading the book and seeing the movie, both during my childhood, I only recently connected the two. To be honest, they don't have terribly much in common apart from character names. In the book, Basil idolizes Sherlock Holmes and spends many hours observing the great detective. the movie's Basil may as well be Holmes and barely seems aware of his human counterpart. The plots are entirely different. The book deals with the kidnap-for-ransom of two mouse children, lured away by their abductors with candy. In the movie it is the father who has been taken by the villainous Ratigan in order to overthrow the queen. Perhaps the Disney writers thought that children would respond poorly to the notion of being kidnapped (though you would think the idea of having your parents stolen would be far worse) or perhaps they were simply looking for a plucky young heroine. Notably, each version of the story tells us something about the era. the book was published in the 50s and stars adults who rescue children who's foolishness allowed them to be captured. The movie was released in the late 80s and is far more action oriented, showing a young girl acting on her own. 
If you're fond of an older writing style, a traditional detective, stick with the book. But if you like more humor, songs, and child heroes the movie is well worth watching.