San Francisco is standing on the brink of disaster - it sits on one of the world's most infamous earthquake hotspots – the San Andreas Fault. How do the city's buildings and infrastructure survive the onslaught of a destructive earthquake? This film looks beneath the city's skin to discover the engineering wonders and geological forces that make it possible. Stunning CGI animation peels back the glass of its skyscrapers and steel off its bridges to reveal their inner workings. The engineers and geologists who know this city the best reveal the secrets inside San Francisco's skyscrapers that keep them standing, protect them from raging fires and keep residents safe during the deadliest quakes. The film explores the geology that shaped the city's past and challenges its future, from the valleys that hold the city's fire-fighting water to the fault line that is overdue for a massive earthquake.