Fievel, while in Texas with his parents, meets Mrs. Brisby, and they become friends afterwards, however, Fievel's life takes a turn for the worse when his sisters are captured, and his parents are killed by the evil Cat R. Waul. And Mrs. Brisby decides to become Fievel's adoptive mother while helping him find his sisters, stop Cat R. Waul's plots and return to New York City. This is set in the present day modern times.
Fievel: Hi Ma'am.
Mrs. Brisby: Hello.
Fievel: My name's Fievel Mousekewitz.
Mrs. Brisby: I'm Mrs. Brisby.
Fievel: Um... Mrs. Brisby, Can i try on your amulet please?
Mrs. Brisby: Why certainly. May I try on your hat?
Fievel: Mmm-hmm. (He wears Mrs. Brisby's amulet, and Mrs. Brisby wears his hat)
Cat R. Waul: Gentlemen, Today is the day we get what we want, (showing the picture of a dead mouse between a bun.) Mouse-Burgers!
Cat Gangsters: Mouse-Burgers!
Cat R. Waul: Let me hear it again!
Cat Gangsters: MOUSE-BURGERS!
Cat R. Waul: LET THE SALIVA FLOW!
Cat Gangsters: MOUSE-BURGERS!!!
Cat R. Waul: And we are going to do it... With THIS! (revealing a giant mousetrap.)
Cat R. Waul: Jolly good. Now pay attention. Cats and gentle mice, lend me your ears. It is my distinguished pleasure to invite all of you... to share our dinner... triumph! To share our triumph! Today we herald in a momentous... new feast... ival. "Feastival..." festival. To mark this brilliant and illustrious snack occasion, I will, with these golden scissors, hereby cut the red... ribbon.
Fievel: I tried to warn my family, but it's no use, Cat R. Waul is taking over, He kidnapped Tanya and Yasha, turned my Mama and Papa into Mouse-Burgers and opened a saloon. Now I'm too late. The cats made an orphan and all alone.
Mrs. Brisby: Oh that's too bad, but don't worry. I'll be your mother now, and I'll adopt you as a new member of my family.
Fievel: You think so?
Mrs. Brisby: I know so.
Mrs. Brisby: (to Fievel) Your sisters are alright, and they're out there somewhere.
The film was originally going to be co-distributed by 20th Century Fox international, However in light of the acquiring of 20th Century Fox and its assets by the Walt Disney Company and Metro Goldwyn Mayer ending its distribution deal with Fox, 20th Century Fox dropped out of the production leaving it with only Universal Pictures and Metro Goldwyn Mayer.