The perils of wartime add special urgency to latest mysteries being investigated by Nuala Anne McGrail and her adoring husband, Dermot Coyne.   More than a little fey, Nuala has a well-deserved reputation for getting to the bottom of even the most tangled intrigues, even when they may be taking place on the other side of the world.   Desmond Doolin, an idealistic young man from their West Side Chicago neighborhood, has gone missing in Iraq.  Having flown off to the Middle East in the name of peace, he hasn't been heard of since.  The U.S. government denies any knowledge of his whereabouts, and his grieving family has all but written him off as dead, but Nuala is convinced that there's more to the story . . . and herself won't stop asking questions until she finds out what has really become ofDesmond, one way or another.   Meanwhile, a parallel investigation uncovers the story of another young man abroad in dangerous times.  Poking around in the past, Dermot and Nuala happen upon the memoirs of Timothy Patrick Clarke, the Irish ambassador to Nazi Germany, who risked his life for the sake of a beautiful German widow . . . and a secret plot to kill Adolf Hitler.   Working together as always, Nuala and her husband find themselves engrossed in the secrets of the past, the present, and two very different wars.    Irish Linen is another captivating installment in a series thatPublishers Weekly calls "immensely entertaining."