Bangalore grew from a garden city into India's tech capital, and now its 13 million residents face a water crisis that could turn the metropolis into another Cape Town, one of ten megacities the film names as candidates for 'day zero,' the point at which taps run dry. DW's camera crews follow residents hauling water from tankers, engineers pumping groundwater from wells sunk hundreds of feet deeper each year, and officials struggling to explain decades of unchecked construction that paved over the lakes the city once relied on. Interviews with urban planners, hydrologists, and local politicians lay out how sprawl, weak zoning, and drought cycles worsened by climate change combined to strain the supply. The film widens its lens to Mexico City, Beijing, Barcelona, and Melbourne, comparing how each city is responding to the same stress test. Rather than offering easy fixes, it tracks proposed solutions, from lake restoration to stricter groundwater regulation, and asks whether any of them can outpace the growth that caused the shortage in the first place.