By 1865 the Great Western Railway had spread across Cornwall changing the face of the countryside with earthworks and viaducts. Now a new line is under construction bringing with it an army of navvies who are feared by the locals, ill-used by the railway company, and a source of amusement for bored aristocratic ladies. Two men and two women of vastly differing backgrounds are drawn together by corruption, intrigue and tragedy. In the wake of disaster each must make choices and the stakes are high.