One of the earliest drafts of the film was written by Steven Barnes, who received a creative consultant credit in the final product and was closer to the original novel. The story would have focused more on the rats and their time at NIMH as it did in the book, which was reduced to a short flashback in later revisions to bring Mrs. Brisby and her plight into the forefront. It also included a female rat named Isabella (described as "a young, cute, somewhat motor-mouthed rat with a crush on Justin"), who was ultimately left out and much of her dialogue given to Nicodemus. A revised synopsis dated July 2, 1980 by an unattributed author would take the movie closer to its completed form, which ended with the mysterious disappearance of the rats, leading the characters and audience to wonder if they ever really existed, or were just an elaborate illusion.