Duplicity / Shawn Wilson.

Enhanced descriptions from Syndetics:

This was not the homecoming Brick envisioned



After the trauma of his last case, and after three months spent recovering in Ireland, life is looking up for newly retired homicide detective Brian (Brick) Kavanagh. Back home in Washington, D.C., a new job shows promise when he's asked to train criminology students in cold case techniques.



Then he's off to a whirlwind weekend in Chicago with Nora, an Aer Lingus flight attendant he'd met in Ireland. There he receives shocking news that his former partner's wife and twin infants have been kidnapped. Brick rushes to D.C. to support Ron, the man who's always had his back--but as days pass, Brick questions how well he really knows this man.



Brick's cold case--the unsolved hit-and-run death of a college student--is heating up. Brick finds gaping holes in the original investigation. Is it possible diplomatic immunity granted someone a "get-out-of-jail-free card"?



Meanwhile, Ron's family tragedy unfolds in a most bizarre manner, and the escalating cold case points to D.C. corruption at the highest level. Things are getting complicated . . . very complicated . . . and dangerous.



Duplicity is perfect for fans of Michael Connelly and Robert Crais



While the novels in the Brick Kavanagh Mystery series stand on their own and can be read in any order, the publication sequence is:



Relentless

Duplicity