Sonny Graham is fishing on a large Canadian lake when he decides to explore a small island that has long fascinated him. As he wades ashore to tie up his boat he notices two men standing in the shade of a nearby tree. Sonny doesn't want company and ignores the two strangers, but they insist on making his acquaintance. During the next several hours they relate an incredible story of how they've accidentally passed through from a troubled community existing in another dimension on the lake. As he listens, Sonny realizes that the strangers believe he's an elusive prophet they've been seeking and that they expect him to help saver their world from imminent disaster. Sonny, who suspects they're either criminals or insane, agrees to help while secretly planning to abandon them at the first opportunity. By the time he discovers they're telling the truth, it's already too late to back out. And it's only then that he realizes far more is expected of him than he's willing to give.