Young Tony Thompson (Jonathan Lipnicki) moves with his family to Scotland from California, where his family takes up residence in a small castle while his father is employed building a golf course on the estate of Lord McAshton. Since arriving in his new home Tony has experienced recurring nightmares about vampires and a mysterious comet. Things also don't get any better for him at school as he gets picked on by bullies who happen to be the grandsons of his father's new boss.
One night, while dressed up as a vampire, Tony is mistaken for one by the young vampire Rudolph (Rollo Weeks), who is on the run from the evil vampire hunter Rookery (Jim Carter). Tony helps Rudolph find a cow to feed from, and in return Rudolph takes Tony flying. The two boys quickly become friends, and Rudolph confides to Tony that his family only drink animal blood and wish to become human. Rudolph reveals that they are searching for a magical amulet than can be used to turn vampires into humans, but Rookery is also seeking to use the amulet against them. When Rudolph takes Tony to the cemetery where his family lives, they are confronted by Rudolph's parents Frederick (Richard E. Grant) and Freda (Alice Krige) and Rudolph's romantic sister Anna (Anna Popplewell) and rebellious teen brother Gregory (Dean Cook). Frederick doubts Tony's loyalty to his son, but when Tony helps repel an attack from Rookery, Frederick begrudgingly allows Tony to help them. Tony and Rudolph then proceed to get revenge on Flint and Nigel, the school bullies who beat Tony up everyday.
Rookery alerts Lord McAshton to the presence of vampires in the village. Lord McAshton reveals that his family has known about the existence of vampires for generations. Elizabeth, an ancestor of Lord McAshton, was romantically involved with Rudolph's uncle Von, who was the last known holder of the amulet, and both lovers were killed by the McAshtons. Learning this, Tony, Rudolph, and Anna seek out Elizabeth's tomb, where Tony experiences a vision pointing out the location of the amulet: Tony's own bedroom. Rudolph and Tony race Rookery to the amulet while the rest of Rudolph's family, along with Tony's parents, travel to the site of the ritual the vampires hope to perform.
Tony and Rudolph succeed in bringing Frederick the amulet, but the ceremony is interrupted by Rookery. The vampires are unable to stand against Rookery's glowing cross, but Tony's parents and Tony to complete the ceremony by wishing for the vampires to become human. Rudolph and his family disappear as the comet passes, leaving Tony and his parents alone. Some time later, while visiting the village market, Tony spots Rudolph and his family, now human, moving into a house in the village. At first they seem not to recognize Tony, but as he calls to them their memories return, and the friends are reunited.
Who helps Rudolph find a cow to feed from, and in return Rudolph takes Tony flying
Tony