It Begins In Betrayal - Iona Whishaw

Summer descends over the picturesque King's Cove as Darling and Lane's mutual affection blossoms, but their respite from solving crime is cut short when a British government official arrives in Nelson to compel Darling to return to England for questioning about the death of a rear gunner under his command in 1943.
In Darling's absence, Ames oversees the investigation into the suspicious death of a local elderly woman and uncovers a painful betrayal inflicted forty years earlier. Meanwhile, Lane follows Darling to London, where he is charged with murder and faces hanging. While desperately seeking answers, Lane is presented with a desperate proposal that could save the man she loves, but only if she returns to the very life she sought to leave behind.