The film was theatrically released on November 14, 2003 with mixed-to-positive critical reception. However, the film was a box office bomb, grossing $68.5 million worldwide against an $80 million budget. This was the final film to be scored by composer Jerry Goldsmith, who died less than a year after the film's release. This was also the final film to be produced by Warner Bros. Feature Animation.
Tired of playing second banana to Bugs Bunny, Daffy Duck demands his own cartoon from Warner Bros., but is promptly fired. Aspiring stuntman DJ Drake is asked to escort Daffy off the studio lot, but the ensuing chase leads to the Batmobile demolishing the studio water tower. DJ is also fired in the process, and returns home with Daffy hitching a ride, discovering his father, action film star, Damian Drake, is actually a secret agent. Damian instructs his son to travel to Las Vegas, find his associate Dusty Tails, and gain the mystical "blue monkey" diamond, but he is shortly thereafter captured by the Acme Corporation, led by the childish Mr. Chairman. DJ and Daffy head for Vegas. Meanwhile, Bugs' routines fall apart without Daffy, so "Vice-President of Comedy," Kate Houghton, is sent to rehire Daffy or face being fired herself. Bugs informs Kate of the situation, so they steal Damian's spy car, and pursue DJ and Daffy.
In Las Vegas, DJ and Daffy meet Dusty in a casino owned by Acme operative Yosemite Sam. Dusty gives them a strange playing card, but when Sam attempts to kill them, they flee in the spy car with Bugs and Kate. The spy car, which can also fly, crashes in the Nevada desert. The group eventually stumbles upon Area 52, run by a woman called 'mother', who informs them of the situation, and plays a video recording, which reveals that Acme intends on using the blue monkey to transform mankind into monkeys to manufacture their products, before turning them back into human beings to purchase them. Marvin the Martian, imprisoned in the facility, escapes and leads a group of fellow alien inmates to obtain the playing card, but the heroes escape. Seeing that the card has Mona Lisa's face on it, the group conclude they must view the painting in the Louvre, located in Paris.
At the Louvre, they discover that the card contains a viewing window, and looking through it, the window reveals that the Mona Lisa has a map of Africa hidden beneath. Elmer Fudd appears, and, revealing himself as an Acme operative, chases Bugs and Daffy through the gallery for the card whilst Kate is kidnapped by Mr. Chairman's bodyguard, Mr. Smith, to obtain a photo of the African map. DJ rescues Kate. Elmer is disintegrated by Bugs after jumping out of a pointillism artwork. Bugs and Daffy reunite with DJ and Kate, and they leave Paris.
DJ, Kate, Bugs, and Daffy travel to Africa, meeting Granny, Sylvester, and Tweety, who escort them to the ruins of a jungle temple where they find the blue monkey. Granny and company reveal themselves to be Mr. Chairman, Smith, and the Tasmanian Devil in disguise. Mr. Chairman uses a disintegration gun to transport himself and the heroes to the Acme headquarters where he forces DJ to give him the diamond, when Damian is revealed to be his prisoner.
Marvin is sent to place the blue monkey on an Acme satellite which will emit an energy beam around the world to turn everyone, except Mr. Chairman, into monkeys. DJ and Kate rescue Damian from a death trap, whilst Bugs and Daffy pursue Marvin into space. Bugs is incapacitated, prompting Daffy to become Duck Dodgers, in order to destroy the blue monkey. The transforming energy beam only strikes Mr. Chairman, turning him into a monkey.
Bugs and Daffy return to Earth, where Daffy discovers the whole adventure was staged to make a film. However, Bugs promises Daffy they will be equal partners, but just as Daffy's luck seems to be improving, he is flattened by the Looney Tunes iris, where Porky Pig attempts to close the film with "That's all folks!" only for the studio to shut down before he can finish, and he tells the audience to go home.