Fast-talking lawyer and habitual liar Fletcher Reede (Jim Carrey) is constantly coming up with excuses for not visiting his four-year-old son, Max (Justin Cooper), who lives with Fletcher's ex-wife, Audrey (Maura Tierney). When Fletcher misses Max's fifth birthday party, Max makes a wish that his dad will stop lying for a whole day. The wish is immediately put into practice, and Fletcher thus finds himself becoming disturbingly honest with his boss (immediately after having sex), his colleagues, and worst of all, in court.