As Memorial Day weekend heralds the beginning of summer, no one in St. Louis is alarmed by a few warm and humid days. Only as the humidity continues to steadily increase worldwide is it apparent that this unprecedented weather could be the death of mankind. As water saturates the air and disappears from the land, one meteorologist begins to suspect that this anomaly isn't a natural one. Survivors flee from dying cities, but meteorologist Wendy Makani remains behind to try to discover the truth behind this lethal aberration. When her research produces startling results, the last thing she expects is for the answers she seeks to come looking for her. Wendy and her new partner must work together against the clock to stop this catastrophe that began in the dawn of Earth's creation.