WHEN CHARLIE BAKER'S PARENTS ANNOUNCE that they're taking him and his sister--the drama queen Clarissa--to a cabin in Maine for two weeks, Charlie thinks they're kidding. Then their mom adds something else. "There's no electricity," she tells them. "And you leave your cell phones at home." They weren't kidding. When the Bakers arrive at Lake Fortune, they are welcomed by a rickety cabin with an outhouse, a thunderstorm, and a creature in...