frankie muniz play jason who be a high school student . his big problem be his life be build on small or big lie that put him into trouble most time . however and he can not escape from his teacher and he finish his creative writing homework just before it deadline . while he be bike fast to hand his homework to the teacher and he crush into a car . a he explain the situation to grumpy man ( giamatti ) in the car and he give him a lift to his school . but the problem be jason leave his homework in the car and the other way of say this be marty wolf ( giamatti ) steal it . after a few month jason go to a movie and see a trailer that take him aback . because the story of the movie be base on his homework . he tell that to his parent but of course they do not believe him . especially his father use word which insult him . jason decide to go to la and find wolf to tell his father that jason be not a liar . when wolf refuse it and jason take action and ruin his life . this be the short story of the big fat liar . well and a a kid movie it might be a light hearted one but there be some error that even could would ask if that be possible . such a and have such a small amount of money and go to la with a friend to sort the problem out and have access to this cinema producer highly protect house and office and set up a telecommunication system overnight . do it seem believable . it do not . well this be a kids movie but kid be not that gullible . big fat liar offer some little pleasure to it target audience . unfortunately and i be not a big fat liar to say that this be a good movie . out of .