Dead Even - Brad Meltzer (Thistle No. 490)

Sara Tate has just started as a prosecutor in the Manhattan District Attorney's office. Her husband, Jared Lynch, is a defence attorney on the brink of making partner at his prestigious Wall Street law firm. 

They have a golden future ahead of them and a terrific, high-spirited marriage until they find themselves on opposite sides of the same case. When that happens, they're both threatened by parties to the case. The result is unavoidable: no matter who wins, one of them will die. There is plot and counter-plot, and nothing is what it seems.