Has it really taken Lathen 20 books about murder-in-business-settings to finally get around to the airline industry? Apparently so. And, once again, though banker John Putnam Thatcher pops up occasionally with a bit of insight (more observation than sleuthing), the absorbing focus is on the suspects themselves--as they continue to cope with business crises while undergoing the ordeal of a police murder-investigation. The airline is Sparrow Flyways of Boston, a small outfit with employee profitsharing (not unlike People's), founded a few years back by charismatic Mitch Scovil, quietly efficient Eleanor Gough, equipment-expert Clay Batchelder, and ambitious Fritz Diehl. Now, however, Diehl has left for a VP slot at a big airline, Mitch is yearning to expand Sparrow into cross-country flights, and his plan is being fiercely opposed by the employee/stockholders. So, when pilot Alan Whetmore, the shrill employee spokesman, is found murdered (bludgeoned with a company wrench!), Mitch immediately becomes suspect #1. Things become more complicated, however, once it's discovered that the dead pilot had been blackmailing some unknown someone--to the tune of $100,000. Also: who has a motive to mire Sparrow in scandal and send its stock plummeting? As often is the case with Lathen, the answers are less interesting than the questions. And readers keen on action probably won't be satisfied by the verbal sparring here--or by the droll mini-drama of an employee walkout on Thanskgiving eve. For Lathen lovers, however, this is a solid--if not superior--portion of the reliable, distinctive formula: fascinating business details, shrewdly sketched characters in nonstop conflict, and the comforting presence of wry onlooker Thatcher (whose trust division controls 20% of the Sparrow stock).