The Higgs boson is the particle physicists spent decades hunting to explain why matter has mass at all, and this film follows that search to CERN's Large Hadron Collider near Geneva, where two seventeen-mile detector teams, ATLAS and CMS, sift billions of proton collisions for a trace of it. Jim Al-Khalili presents, walking through the idea of symmetry-breaking that Peter Higgs and colleagues proposed in the 1960s and explaining why the particle had to exist mathematically long before any machine could find it. Animation breaks down what a collision actually produces and how a detector the size of a cathedral picks one meaningful event out of forty million per second. Interviews with CERN scientists cover the years of false starts and incremental evidence building toward the announcement, and the film closes on the July 2012 result: enough data to call it a discovery rather than a hint. The film treats the theory and the engineering as one continuous story, since neither gets you to the result alone.