Casper's rival from Scare School, Thatch the Bully Vampire stolen Wendy's wand and trapped her, Casper, Kat and Peter to go back in time to see lots of dinosaurs.
Casper the Friendly Ghost and his best friends, Kat Harvey, Wendy the Good Little Witch and Peter Von Trapp are playing tags games at Whipstaff Manor but Miranda told that they can't run in the house while they're playing tags in the halls. Until then Dr. Harvey came with the package and brought it to Peter and he opened the box and it's a kind of toy dinosaur and he like it.
Outside the house the kids are playing with Peter's new dinosaurs toy and they are being watched by Casper's Scare School rival, Thatch the Bully Vampire, but he has a plan to get rid of Casper and his friends so he sneaked behind Wendy and steal her wand and he blast her, Casper, Kat and Peter into millions years ago before time. Thatch was proud of himself for making his rival go back in time and he has Wendy's wand to make him rule the world.
After Thatch blasted Casper, Kat, Wendy and Peter into millions years, they landed into the jungle, they see some creatures whose are predators trying to harm another animal so Casper, Kat, Wendy and Peter started running for their lives. Then suddenly a cave man came and rescue the kids and take them to his cave.
Meanwhile on the present day, Dr. Harvey, Miranda, the Witch Sisters and the Ghostly Trios can't find their kids anywhere so they need help to find their kids in Dinosaur World and they met Mia and her father, Nigel whose told about the reason why they can't find Casper, Kat, Wendy and Peter because an evil vampire has stolen Wendy's wand and then vanished her, Casper, Kat and Peter into the Prehistorical Era from the portal to see some dinosaurs. The Ghostly Trio and the Witch Sisters got very angry Thatch has stolen Wendy's wand to be king of the universe so they, Dr. Harvey and Miranda have to find the time machine immediately.
Back in the past a cave man named, Hugka Waka who told Casper, Kat, Wendy and Peter that he rescued them from those dangerous animals are called Dinosaurs whose are trying to look for the great valley and when do they get tired, they find food and water on the way in desert. Casper, Kat, Wendy and Peter are now being helped by Hugka Waka so they can help those heroes to get out of here as they follow those dinosaurs to the great valley.
Later Casper and the gang just stopped and realized those dinosaurs are hungry and they have to find water for them so they start digging into ground and they must find their friends after the time machine is coming to find them and it's Dr. Harvey, Miranda, Mia, Nigel, the Witch Sisters and the Ghostly Trios, whose told Casper, Kat, Wendy and Peter that they are in danger by those dinosaurs but Hugka said we better feed those dinosaurs with water but they have a plan to get Wendy's wand back from Thatch once and for all.
After feeding those dinosaurs with water Casper wants Hugka to come with him, Kat, Dr. Harvey, Wendy, Peter, Miranda, the Witch Sisters and the Ghostly Trios to the future to help them to stop Thatch before he can take over the world so they have to go to the time machine and then set it back to the future. As they arrived to their own time, Casper, Kat, Wendy, Peter, Hugka, Mia, Nigel, Dr. Harvey, Miranda, the Witch Sisters and the Ghostly Trios see Thatch, who's has Wendy's wand and demands the Mayor of Deedstown to let him to take over the world, but Casper refuses him to take over the world. So he and the gang stop him and grabbed Wendy's wand and tossed back to her.
After Wendy got her wand back, she and her aunts used their powers on Thatch and then they vanished him back to the past where all of the dinosaurs were and then those dinosaurs scare Thatch and chased him away. After that, Casper, Kat, Wendy and Peter thank Hugka for their help and he also thank them for helping these dinosaurs to find food so they can go visit him someday again soon as Wendy used her wand to bean Hugka back to his own time and she did. After Hugka went back to his own time, Casper, Kat, Wendy and Peter told his uncles, her father, her aunts and his mother everything in back in time and they lived happily ever.