Roberta McKinnon, age 11, is a science nerd and big dreamer. She likes to add to this resume, "And guess what? I'm blonde!" She and her best friend, Marilee Evans, are trying to figure out how to beat the impossibly brilliant Henry Horton Harris Helmsby---the 4 Hs of the Apocalypse---at the upcoming science fair. Allagash, Maine, their little hometown, is famous for something called "The Allagash Abductions," when four men from Vermont claimed to have been taken aboard a spaceship while on a trip down the Allagash River. Robbie McKinnon puts her brain to work and comes up with a solution. "If aliens visited Allagash before, they might again. What if we try to contact them? If we interview them for the school paper, we'll win science fair for sure!" But standing in the way is her annoying big brother Johnny, and his best friend, Billy, on whom Robbie has her first crush. After a mean trick played on the girls (it has to do with fake aliens appearing in town) Robbie decides revenge is in the air. It'll serve Johnny and Billy right.

But it means they have to drive their 4-wheelers up on Peterson's Mountain after sundown. Everyone knows the mountain is haunted by the ghost of Cally Peterson. It's while up on the mountain that the girls see for the first time those strange lights in the sky that many townsfolk have been spotting. "This time it isn't your crazy brother," says a frightened Marilee. It's a summer of excitement, but it's also marked by sadness over a death in the family. By the time school is starting again, these two wise young girls have grown even wiser.