Timely yet terrifying, Flood predicts the unthinkable. Could this be the capital's last 24 hours? When a raging storm coincides with high tide, it unleashes a colossal tidal surge which travels mercilessly down England's East Coast and into the River Thames. Overwhelming the Barrier, torrents of water pour into London. The lives of millions of people are at stake. Top marine engineer, Rob Morrison and his father Leonard rush to the aid of his ex-wife and Barrier expert, Sam to try to save a city on the brink of annihilation.