Carrigan is furious to learn from her late father's lawyer Mr. Rugg that she has only inherited Whipstaff Manor in her father's will, rather than anything of significant value. Infuriated, she tosses the will and deed into a fireplace but it is rescued by her attorney and close associate Dibs. Dibs discovers one of the will's pages has an inscription on it describing treasure hidden in the manor. They both leave to find Whipstaff Manor at a town in Freindship Maine.
Carrigan and Dibs visit the old manor, but find that it is haunted by four ghosts: Casper, a friendly but lonely young ghost and his three obnoxious uncles known as The Ghostly Trio: Stretch, Fatso, and Stinkie.
The two make several attempts to remove the spirits including hiring both an amatuar exocist named Father Guido Sarducci, and one of the Ghostbusters (cameo appearance of Dan Aykroid) but are unsuccessful. Carrigan later learns about an afterlife therapist named Dr James Harvey who explains that ghosts are simply spirits with unfinished business and she and Dibs contact him for help.
Carrigan and Dibs meet with Dr Harvey and his daughter Kat at when they arrive at the manor,Dibs introduces himself as "a close personal freind" of Carrigan. Kat responds by introducing herself as Dr Harvey's "close personal daughter". They grab her face and give her each sympathetic looks before letting her go. Carrigan then orders Dr Harvey to remove the ghosts as quickly as possible.. However, things are complicated when Kat and her father meet the ghosts face-to-face; despite Casper's best efforts to befriend them, the two are terrified by both his appearance and the antics of the Ghostly Trio. They choose not to leave, however, and they stay for the night.
Carrigan and Dibs return back to the manor later on as they see Dr Harvey in the library with the Ghostly Trio. They decide to have a "happy hour" with him and drag him out of the manor. This allows them to enter the house and they start looking around for the treasure. They follow Casper and Kat (who are now friends), to Casper's father's laboratory hidden under the floorboards of the library. There they learn that a special capsule is used to run a machine called the Lazarus. This has the power to bring ghosts back to life, but now there is only enough for one. They also see the vault at the end of the laboratory when Kat point's it in the direction while talking with Casper. Seeing as that's where the treasure is Carrigan and Dibs apporoach the vault but finds its locked. Realizing his one opportunity to come back to life, Casper with Kat's help turns on the Lazarus and steps inside. Unfortunately, the capsule is stolen by Carrigan and Dibs and Casper is left disappointed when he turns into an egg yolk. With the capsule in hand, Carrigan and Dibs realize that, as ghosts, they would be able to fly through thick solid walls like the vault to retrieve the treasure, and use the Lazarus to come back to life. Unable to decide who should die, the two attempt to kill each other, resulting in Carrigan falling to her death off of a cliff.
She suddenly reappears as a monstrous ghost to a shocked Dibs and says "not so fast little man the b**ch is back!!".
- Dibs was last seen being flunged out of a window by Carrigan but it is unknown what happened to him afterwards or if he fell to his death when he was flunged out the window.
- Throughout the film it was hinted that he and Carrigan are secretly lovers.
- Dibs is always belittled by Carrigan such as when she calls him names or orders him around to help her.