In the future, in a dystopian Endsville, an evil being known as the "Lord of Horror" orders his henchmen to go back in time to eliminate Billy and Mandy and prevent them from reaching a powerful hand-like artifact that the Lord of Horror has in his possession. Billy and Irwin of this time hope their past selves can stop the Lord of Horror's evil plans. Two weeks prior, Grim is sued for dereliction of duty and misuse of his abilities by his old rival, the Boogey Man, the former having failed to reap General Skarr thanks to an intervention from Billy and Mandy. Grim and the children are set to be exiled by the Underworld Court and placed in the custody of Boogey, with Grim being stripped of his job and powers and Numbuh 3 of as his court-appointed replacement. Boogey reveals it was part of his plan to steal Horror's Hand, an artifact capable of bringing people's deepest fears to life and transforming anyone who conquers their fear into the scariest and most powerful being in existence; Boogey himself believes that with its power, children will fear him again. The group eventually escapes and plans to obtain the hand for themselves for various reasons. Both groups eventually reach where the hand is held, where they meet Horror the Ancient, a living statue that cut off the hand -originally his left hand- having placed his fears within it. To obtain the hand, two rivaling groups must embark on a race across the Cannibal Run - the most dangerous section of the River Styx - as well as facing their worst fears. Grim and the children win and scrape to obtain the hand. Billy, Irwin and Mandy are easily subdued by their respective worst nightmares, leaving Grim to claim the hand unaffected, revealing he lives his worst nightmare every day - living with Billy and Mandy. The hand however is almost immediately stolen by Boogey. Believing he has won, Boogey turns out to be incapable of facing his worst fear, realizing that he is not at all scary. He suffers amnesia after a series of accidents, and ends up afraid of everything. Billy also reveals that he and his friends obtained what they wanted all along without the need for Horror's Hand. After the Underworld Court arrive to make one last attempt to banish Grim forever, Mandy insistently makes them reinstate Grim as the Grim Reaper, because he saved them from a future ruled by Boogey, but also because Numbuh 3 was too much of an optimist to actually reap anyone. In the end, a naked, cut up, future Billy appears before them to warn that if Mandy had used Horror's Hand, she would have taken over the world in two weeks, becoming the Lord of Horror from his time. Grim decides to put the hand in his trunk to ensure that that future never comes to pass. Future Billy eventually goes back to the future to make sure that things were set right. The credits roll, showing what each character did after the events of the film, such as General Skarr using the hole in his chest to keep birds, Mandy becoming the new Captain of Boogey's ship, Numbuh 3 starting her own Reaper-for-hire service, Dracula stealing Grim's scythe for use as a golf club, Billy eventually becoming President of the United States and Boogey living in fear ever since his defeat. The epilogue shows how Billy went back to the future to find that it hasn't changed as Fred Fredburger has obtained Horror's Hand from Grim's magic trunk and took over the world as the new Lord of Horror.
Creating the film was the first time that Maxwell Atoms had created anything with a length of over one hour. That, along with creating the regular season was challenging for him. Boogey Man was chosen as the villain for the film because he was a lesser villain that had a relationship with Grim. This was because Atoms was given the idea to follow a storyline similar to by a Cartoon Network representative. The role of Numbuh Three was originally supposed to be taken up by Pamela Anderson, but she did not take the part. Afterwards, he decided to use Numbuh Two, who is innocent, as a sneak preview of The Grim Adventures of the Kids Next Door, but ended being suggested by Tom Warburton that Numbuh Three be used instead. Atoms also used some Nintendo cameos in the later part of this TV movie, such as when Boogey Man kidnaps Mandy he makes a "warp pipe" appear and its SFX is used when he goes into it The title track "Land of the Dead" was written and performed by Voltaire. It is Voltaire's second collaboration for The Grim Adventures of Billy & Mandy, the first being on the episode "Little Rock of Horrors" with the song "BRAINS!". The film's end credits also feature Boogie Wonderland by Earth, Wind & Fire. The film is most famous for its original song "Scary-O".
Home media
The film was released on DVD by Warner Home Video in the United States on April 3, 2007. The DVD contains both anamorphic wide screen and modified full screen versions with 5.1 surround sound and regular stereo sound. Special features include the original "Bully Boogie" episode that Boogey originally debuted in and interviews with the voice actors.
Reception
The film received generally positive reviews from critics. Dennis Prince of DVD Verdict reviewed the movie saying, "All told, Billy & Mandy's Big Boogey Adventure is a gift from Atoms, and an indulgence of all the goodness and gooeyness that has made the series a top draw on Cartoon Network. Despite the boogers, bare buttocks, and boorish humor, this court finds no real crime has been committed. Case dismissed". MaryAnn Johanson, of The Flick Filospher reviewed the movie saying "'Full-length movie. Full of boogers!' promises the blobby green sticker on the DVD. And it's true. But somehow, the tons of gross-out potty humor manages to be delightfully goofy -- perhaps it's the irresistibly cheerful spin cartoonist Maxwell Atoms puts on his demented twisting of kiddie cartoons" It was nominated for an Annie Award for Best Music in an Animated Television Production.
