It is a sad day in the treehouse, when Chubbo, one of the KND's power-providing hamsters passes away; and it is saddest for the overly sensitive Numbuh 3, who even maintains a vigil at his grave until the weather proves inclement. But unwise is the one who mourns too long for the dead, because during the dark and stormy night, a gang of ghostly hamster arrive, and drag the terrified Three to the hamster afterlife! Now the team must penetrate the very netherworld to rescue their friend, but can even the KND overcome a mob of restless rodents?!

Numbuh 4 learns he is to be sent to a boarding school but he isn't worried, as he's always escaped from them before. But then he learns that the school is being run by the evil child Madam Margie, a girl who is getting high-tech aid from none other than her future self! Madam Margie's abominable plan is to create a twisted utopia where girls rule the world, using a demonic weapon called the girlifying ray that can turn anything feminine! The team seeming doesn't stand a chance until they recieve aid from a strange source Numbuh 4's OWN future self!

Hoagie and the gang go to the KND Academy to watch his brother Tommy graduate while Father plans an all-out attack.

Numbuh 4's disgust at anything Rainbow Monkey only increases when he finds himself trapped on Rainbow Island.