Industry in Yorkshire is booming and the cities are expanding. This growth will come at a price: which of two rural valleys in Nidderdale is doomed to be dammed and flooded to quench the cities' thirst? Rachel Garnett is determined to fight for her lovely valley and their way of life. Working against her is a young engineer, Roger Beckwith, who is planning a reservoir that will swamp the parish of Firby.
Rachel works at Firby Hall, an Elizabethan mansion that will be demolished when the reservoir is built. Her father is the farm manager. The owners, Major Potts and Lady Agnes, want to sell the estate but Rachel convinces the Major to save it. When he dies in dreadful circumstances, the sole heir is Guy Potts. A gambler, desperate for money from the sale of Firby Hall, Guy harasses Rachel and looks set to ruin Rachel's careful work.
Rachel must fight on to save her home before destruction carried out in the name of progress threatens to destroy the land.