Sixteen year old Tom Clarke is a wizard - like his late mother and his grandma Ursula but not his father Michael who disapproves of his son using magic to help his school football team. On a field trip to standing stones Tom and his friend Ben find a magic ring,dropped by father and son wizards abducted by the Nekross,aliens who have come to Earth to extract magic from its practitioners. One of the Nekross,Varg,arrives on Earth and captures Tom and Ursula,imprisoning them on their space craft.

Ursula and Randal cast a shrouding spell to shield earthly magic from outer space but the Nekross send a ferocious cat-like creature - the Grazlax - to hunt down Tom when he is at Benny's house. They lock it in the shed whilst Tom casts a spell to divert Benny's parents but when it escapes they force it to retreat,using a hair dryer which kills it.. Unfortunately three more Grazlax babies are released.

Desperate to learn more exciting magic and feeling nagged by his father Tom is happy to befriend the older Jackson Hawke,who uses magic to strip a gang of youths out to mug Tom and who has successfully eluded the Nekross. He is a very powerful young wizard but he uses his magic to play cruel practical jokes,which alarms Benny. Then Benny himself is caught by the Nekross Varg.

Lexi,the Nekross king's daughter,puts on a necklace which transforms her into a human woman and,calling herself Lucy, travels to Earth and befriends Tom. A cautious Benny,however,is suspicious and realises who she really is. Stephanie Gaunt,a fabulously wealthy woman,has been observing Tom and kidnaps him for his powers,along with Lexi,whom she eventually unmasks as an alien. Benny persuades Ursula to form an alliance with the Nekross to free the pair but Varg and his father plan to renege on the deal as soon as the rescue is effected.

Ursula casts a spell to send the Nekross into deep space but only succeeds in making them travel a very short distance but Benny comes up with a detailed plan - which blows up all the school computers - to gather all the exobytes in the universe to defeat the aliens and sends it to them via an email. However when they switch it on it immobilises all the ship's life support systems,dooming them to die within the hour. As the wizards and their friends are celebrating Benny's victory the Nekross appear on his computer and Lexi appeals to Tom to save them.

Tom is having nightmares of the night,ten years earlier,when,on Halloween,his mother Helen died after protecting him from an alien force. Soon afterwards he starts to see her and Randal explains that she is a 'pale shadow',come to warn him of danger. Eventually he meets her but she has no memory of who she or Tom are. She directs him to a warehouse,which was her most recent memory but the warehouse is occupied by Nekross,who are making clones of Helen to obtain her magic.