Daniel Hillard (Williams) is an unconventional artist who specializes in dubbing voices for animated film. Daniel is a kind man and a affectionate father, but he's a poor disciplinarian and a unstable role model. After throwing an elaborate and devastating birthday party for his son, Daniel's wife Miranda (Sally Field) reaches the end of her endurance and files for split. Daniel is brokenhearted when Miranda is given protection of the kids, and he's only permissible to visit them once a week. Determined to stay in contact with his kids, Daniel finds out that Miranda is looking for a housekeeper, and with aid from his brother Frank (Harvey Fierstein), a makeup artist, Daniel gets the post masked as Mrs. Iphegenia Doubtfire, a strict but caring Scottish nanny. Daniel pulls off the trick so well that neither his ex-wife nor his children identify him, and in the course he discovers how to be the excellent parent he should have been all along. On the other hand, Daniel also has to deal with the Miranda's new boyfriend, Stu (Pierce Brosnan).