Set in 1994, The Coast Road tells the story of two women—Izzy Keaveney, a housewife, and Colette Crowley, a poet. Colette has left her husband and sons for a married man in Dublin. When she returns to her home in County Donegal to try to pick up the pieces of her old life, her husband, Shaun, a successful businessman, denies her access to her children. The only way she can see them is with the help of neighbour Izzy, acting as a go-between.

Izzy also feels caught in a troubled marriage. The friendship that develops between them will ultimately lead to tragedy for one, and freedom for the other.