Brock Potter, moody securities analyst and amateur sleuth, uncovers a network of East German spies--in a very downbeat but mostly satisfying successor to such brighter-toned puzzles as Shroeder's Game and Lucky Devil. Kevin Rand, son of the family which virtually adopted college-kid Brock years ago, has been killed in prison, where he's been since being convicted of leaking high-tech satellite data to the East Germans (from a position which Brock helped him to get). Why was Kevin murdered? Is it because he was about to reveal the name of his spymaster, someone (theorizes Mrs. Rand) in Brock's social circle? Troubling questions--which become more so when Brock, on business, visits ailing Arden Electronics and is told that they too were recently infiltrated by a spy for Berlin. Before Bill Arden can tell Brock the whole story, however, he is shot dead by a sniper--as is (a shocker for series veterans) Brock's longtime girlfriend Carol. And so Brock goes sleuthing with a vengeance, looking up Kevin's old girlfriends--at least one of whom has crucial information about the suave N.Y.C. types who are systematically getting treason-prone engineers and executives placed in high-security positions. Strong and somber, if not always convincing: a solid addition to a distinctive, classy series.