Fletcher Reede is a divorced defense lawyer living in
Los Angeles who loves spending time with his young son, Max. However, he has a habit of giving inappropriate precedence to his career, breaking promises to Max and his ex-wife Audrey, and then lying about the reasons. After Fletcher misses Max's 5th birthday party when senior partner Miranda lures him into having sex in the office to land a promotion, Max makes a birthday wish for Fletcher to be honest for one day. Fletcher soon discovers that he is unable to lie, mislead, or withhold the truth. This alienates him from Miranda and his secretary Greta, gets his car
impounded when he confesses all of his
traffic infractions and unpaid parking tickets to a police officer, and causes him an inability to bend the truth in court. Fletcher's newest client is Samantha Cole, a
gold digger who wants to get around a pre-nup with her soon-to-be ex-husband, Richard Cole. The main witness, Kenneth Falk, with whom Samantha has been cheating, is eager to lie when he takes the stand. However, Fletcher finds in court that his inability to lie includes not being able to
suborn perjury. Meanwhile, Audrey is considering a move to
Boston with Jerry, who proposed upon receiving a job offer there. Although they have not been together long, she accepts, to protect Max from future disappointments that Fletcher may cause him. Catching wind of Fletcher's inability to lie, Miranda tries to get him fired by baiting him into insulting Mr. Allan, a senior partner at the firm, but this backfires when Mr. Allan and his board mistake Fletcher's accurate insults for lighthearted roasting. Fletcher tries to delay the case by staging an assault on himself in the men's room, but he's unable to lie his way into a
continuance, specifically because his only possible grounds were, "I can't lie." Knowing that he cannot refute the proof of Samantha's
adultery, her grousing accidentally reveals her real age. He successfully disputes the validity of her
prenup, signed as a minor without
parental consent. The judge rules Samantha is entitled to 50% of Richard's marital assets, allowing Fletcher to win the case truthfully. However, Samantha then pivots to
demanding custody of their children for extra
child support payments. Fletcher watches as she pulls her crying children out of Richard's arms. Horrified by the outcome his actions have caused, he overreacts and demands the decision be reversed. The judge thinks Fletcher is mocking him and holds him in
contempt. Fletcher calls Audrey to bail him out, but she informs him that their plane leaves for Boston that night. Greta, realizing he turned over a new leaf, pays his bail. Fletcher rushes to the airport, but Audrey and Max's plane has left the gate. In desperation, he hijacks a mobile stairway to pursue the plane onto the runway. He keeps his promise to greet Max before takeoff, through a plane window, and gets the plane to stop but is injured. On a stretcher, Fletcher vows to Max that he will spend more time with him. He says that despite the fact that he is free to lie now that the 24 hours have elapsed, it feels more clear to be honest. Max believes him, and Audrey, encouraged by Jerry, decides to remain in California. One year later, Fletcher and Audrey are celebrating Max's 6th birthday. Max makes a birthday wish, only to find that Fletcher and Audrey are kissing when the lights come back on. Fletcher asks Max if he wished for them to get back together, but he says he only wished for
rollerblades. ==Cast==