When the Philadelphia bank Eileen Townsend works for transfers her to Europe, she takes her sons (teen-age Chris and 10-year-old Max) to stay with her uncle Gustav Helsing. Gustav's passions in life are schnitzel, polka music and, we will come to find out, hunting Dracula, who is living nearby as businessman Alexander Lucard. Also living with Gustav is teen-age Sophie Metternich, who impresses Chris. Max is also obsessed with vampires, and not knowing about Gustav's quest, he misreads several signs and becomes convinced that Gustav is a vampire. With his mother away on an assignment, Max goes to the only other adult he knows, the businessman his mother had introduced him to at a reception the previous day, Alexander Lucard. At Lucard's urging, Max lures Chris and Sophie to Lucard's castle. Upon their arrival, Lucard reveals his true nature. Max and Chris get away, but Sophie is left in Dracula's clutches. Unable to reach Gustav, Chris and Max return to the castle to rescue Sophie.

Walter and Anna Dyson, Gustav's old friend and former girlfriend, come to stay at the house. Unknown to Gustav, Max has removed the Cross of the Magyars from the house to have it blessed. It is this cross which keeps vampires from entering the Helsing home, and Lucard finds out that it's been removed. Unfortunately, the cross is returned at the last minute, and it drives Dracula from the house in a blaze of light.

Gustav and one of his former students, Arthur Bauer, find a rare herb and develop a formula called the quinidrine solution, which they hope will reverse the effects of a vampire's bite. When Arthur is kidnapped, Gustav allows himself to be captured by Lucard so that he can test the solution on himself and Arthur. But the formula doesn't work, because Max has confused it with his high protein energy drink and has consumed all the quinidrine. When the kids arrive to free Gustav, Max is able to fend off Lucard and his lieutenant, Klaus, by firing energy bolts at them through his fingers. They escape back to the house, where the kids quickly use their last remaining quinidrine leaf to mix up another batch of the solution for Gustav and Arthur. Gustav is saved, but Bauer chooses to reamin a vampire. He attacks Gustav, but doesn't know about the Cross of the Magyars, the house's protective talisman...which then destroys him.

Max brings home a bungling vampire-hunting scientist, Magnus St. John-Smythe, who insists that a new laser gun he's developed can destroy vampires using concentrated sunlight. Magnus' benefactor in the project, however, is Lucard himself, eager to learn if such a gun is possible. Lucard determines that Magnus' invention is a waste of time and money when it has no effect on a vampire colleague. Incensed, he's about to vampirize Magnus, when Gustav and Max barge in and stop him. Later, at Lucard's castle, the vampire colleague suddenly disintegrates and Lucard becomes the proud owner of the world's only delayed-action vampire gun...which he then destroys.

An archeologist, Dr. Cross, uncovers the resting place of Lucard's ancient and bitter rival, Nosferatu, who tries to bring down Lucard's economic empire. Nosferatu is powerful, with the ability to disguise himself by transforming into guises as innocuous as Gustav and Max. With the assitance of Dr. Cross, he nearly destroys Lucard. But Lucard has help from an unusual source...Max.