A sail boat can tip over and come back up again. Sailors call this a knockdown. In eighteen hours a mega tsunami will hit the Pacific Coast. It will leave in its wake massive destruction and the threat of an ice age. Sixteen-year-old Toni, her brothers, and their friends race the clock as they sail Toni's family boat far out to sea. They must get beyond where the wave crests, or the boat will be crushed. Without their parents to guide them, the reluctant crew improvises. Romances bloom and tempers flare. There is no privacy. Cell phones won't work. The engine breaks down. They are running out of time. Even if they survive the wave, there is nowhere in this ravaged world to go. When disaster strikes, it is up to Toni to find the strength to lead the crew when her brothers cannot.