1957. Barely a decade after the first use of atomic bombs, the world is divided and fearful of the real threat of nuclear weaponry. In an effort to understand the devastating effects of radiation, leading scientists and academics-world-renowned "Thinkers"-are invited to a conference in the small town of Pugwash, Nova Scotia. Two local children, Conni and Jamie, take interest in some of the Thinkers, who are humbled by their innocent welcome. But a spy disguised as a reporter has conned Jamie for information to use against the Thinkers, putting the entire conference-and the town of Pugwash-at risk.