In his attempt to get back on his long-lost love?s good side, Larry visits the school where she works and makes a horrible mistake ? he accidentally tells a child that the Tooth Fairy is just a myth. Crushing the child?s dreams sets off a chain of events that are far more than Larry bargained for, including being ?sentenced? to become a Tooth Fairy or face having his memories erased for good?Larry is brought before a 500-year-old Tooth Fairy stuck in a 10-year-old girl?s body (played by newcomer Brady Reiter) for sentencing. The Tooth Fairy demands that Larry make retribution by temporarily serving as a Tooth Fairy and proving that Tooth Fairies really do exist. His mission? Larry must collect 20 teeth in 20 days. With his orders in hand, Larry embarks on a journey to prove the existence of Tooth Fairies and to win back the love of his life.

Martin Riggs and Roger Murtaugh, after escaping death from the previous movies are put on a hit list by The Triads. When blood thirsty mercenaries are on their tail they team up again with Leo Getz and Lorna Cole, a newcomer (Chris Rock) to finally put an end to the Triads for good.