Laura, an impoverished Cornish girl, meets her husband when they are both in service in Teignmouth in 1916. They have a baby, Charles, but Laura's husband returns home from the trenches a damaged man, already ill with the tuberculosis that will soon leave her a widow. In a small, class-obsessed town she raises her boy alone, working as a laundress, and gradually becomes aware that he is some kind of genius. As an intensely private young man, Charles signs up for the navy with the new rank of coder. His escape from the tight, gossipy confines of Launceston to the colour and violence of war sees him blossom as he experiences not only the possibility of death, but the constant danger of a love that is as clandestine as his work.