A Matter of Honor (1984) by William P. McGivern

When Mark Weir, a Chicago homicide lieutenant, starts investigating a series of murders of army servicemen, he comes on a smuggling “loop” set up by two army sergeants between Frankfurt, Germany, and Chicago. With the help of a striking Chicago newspaperwoman, his ex-wife, Lieutenant Weir begins to fit the pieces together... when he is suddenly gunned down. It is his father, a retired general who wants to assuage the bitterness that divided father and son during the Vietnam years, who decides to avenge his death — by taking on the son’s mission himself, as a matter of honor.

Set against the backdrops of Chicago, Washington and NATO Europe, A Matter of Honor races with edge-of-the-seat excitement to a climax as startling as it is original.