In this series opener, two American brothers, Max and Chris, are left behind in Europe with their eccentric uncle Gustav while their mother travels on business. While Chris spends his time pining for American television and attempting to romance a young music student also living with Gustav, the younger brother, Max, who happens to be a supernatural enthusiast, is positive that his uncle is a vampire and goes to see multi-millionaire Alexander Lucard for help. Little does he know that the rich businessman is hiding a secret of his own.
Gustav's old friends, Peter and Anna Dyson, visit for a short time while Max takes the Cross of the Magyars (an artifact which prevents vampires from entering) from the house to be blessed. When Lucard finds out the cross has been removed, it is a race to see whether the cross can be replaced before Lucard pays the household a visit; but how did he find out that it was gone...?
Gustav and a former student of his concoct a mixture, a solution called quinidrine, which should reverse all effects of an early vampire bite. Gustav allows himself to be captured and bitten by Lucard with the intention of testing it, however, Max has inadvertently switched the solution with a protein drink he made for himself. Upon realizing the mix-up, Gustav and his former student, who has also been bitten, must wait for the children to save them in time to create more of the solution in order to save themselves.
While Sophie and Chris skirt around the relationship issue between them and finally end up on a date together, Max meets a clumsy, but brilliant, scientist who has made it his life's work to invent items for battling the undead. Unfortunately, one of the items he is working on, an Anti-Vampire Gun (which fires amplified sunlight), is being sponsored by none other than Alexander Lucard. When the gun doesn't work as planned, Lucard decides to rid himself of the bungling scientist, leaving Max and Gustav to attempt a rescue before it is too late.
When a man named Paul Yeager loses his wife to Lucard's second-in-command, Klaus (Geraint Wyn Davies), he attempts to enlist Gustav to help him kill the vampire. Gustav, however, is strangely unwilling to give aid in this, even going so far as to warn Klaus that Yeager is after him. While the children are led on a treasure hunt by a scheming Lucard, we eventually learn why Gustav is so evasive regarding Klaus and also why he is so uncooperative in bringing about his death, choosing instead to trap him in his crypt with help from an unlikely ally.
Chris lands a job with a local art house, run by a lovely art dealer named Julia, who also happens to have dealings with Alexander Lucard. When Sophie discovers that Julia is selling stolen paintings, she and Chris visit the art house to determine whether Julia is aware of the thefts and end up discovering that Julia is not only aware but also selling copies of the stolen paintings. When Lucard invites Julia to the castle for a private unveiling of the painting he purchased, Gustav and the children follow in a rescue attempt, but Lucard has plans of his own for his ...