Can you outrun eight legs? Twelve-year-old Andi loves everything about spiders -- they're endlessly fascinating creatures. So when she finds a species she's never seen before at a classmate's Halloween party, she's over the moon. Until the spiders start to behave in unusual and threatening ways, that is. They can camouflage themselves incredibly well, they can jump higher than she's ever seen, and their webs are strong. Maybe even strong enough to trap a person . . . Andi and her friends Carly and Devon try to find an adult to help, but make a terrifying discovery: the parent chaperones have been immobilized by the spiders. As the only ones who know what's going on, Andi, Carly, and Devon will have to take on the spiders themselves -- before it's too late!