A Pact of Silence — David Armstrong

In the long, hot summer of 1969, two young men are involved in the accidental killing of their boss in a Shropshire market town. Traumatized, they conceal his body, but leave behind a vital clue. Four decades later, DI Frank Kavanagh and DC Jane Salt's relationship is in trouble, and Jane, desperate to escape the bad atmosphere between them, escapes to a friend's home in that same Shropshire town--only to find herself in peril...