Invasion of the IQ Snatchers - Arthur Slade - Bog

Can two kids stop a sinister plot to steal the brain power of the people of Nanaimo?
Someone is delivering plates of scrumptious Nanaimo bars to every household in Nanaimo, and the people who eat them are behaving very strangely. Gordon Whillickers doesn't get to eat his because, at the last minute, a hairy arm reaches through his window and steals them. He and Sophia chase after the thief and meet an amazing Sasquatch named Cheryl, who is also puzzled by the sudden appearance of the mouth-watering delicacies.
With the help of Cheryl and the technological wizardry of a local librarian, the two kids move ever closer to the alien creature at the centre of the plot. They must stop him before the Nanaimoites' IQs are lost forever!