Watch An American Tail: The Mystery of the Night Monster (1999) full movie online.
Synopis: Follow the clues to fun and excitement as the beloved little mouse takes on a big monster in this charming, full-length adventure. When a ferocious, mouse-nabbing creature puts fear into the hearts of New York City’s rodents, Fievel and his friends team up with a reporter to chase after the scoop of the century and — just maybe — get a close-up look at the bad guy himself! Featuring three original songs and the voice talents of Dom DeLuise, Lacey Chabert and Robert Hays, An American Tail: The Mystery of the Night Monster is a mischievous, musical good time that the whole family will enjoy!
More info: IMDB Wikipedia