Kyle (Black Camelot, In Deep) always adds a tangy twist or two to his brusquely elegant thrillers--and here, with perhaps some inspiration from Katharine Hepburn in The African Queen, he flavors a solid treasure-hunt tale (set in the early 1960s) with the character of a middle-aged spinster-heroine who tramps through the wilds and shows up every man in sight. She's Charity Franklin, a retired Borneo missionary who calls on hospitalized George Tunnicliffe (our engaging narrator) after George has gained some notoriety for foiling a bank robbery. Miss F., it seems, was with George's pilot father 20 years ago when he crashed his plane on Borneo and died; she gives George his dad's dying letter, which contains a mysterious reference to a number--156.5. George is unimpressed. But when he's then lured to Jamaica by yet another of his dad's old acquaintances--a war buddy and fellow thief who paid off George's dad in rubies--George realizes that his dad's crashed plane was loaded with a fortune in gems. And naturally he's now hot to hunt for the treasure-plane (despite the guerrilla warfare raging in Borneo). But only Miss F. knows the approximate location of the crash, and she firmly insists a) that she go along, and b) that most of the booty be donated to missionary work. So, once Miss F. has proved her physical mettle--by mountain-climbing and knocking off two hired assassins (connected with George's bank heroism)--they're on their hazardous way: rough seas (""Need I say that Miss Franklin was entirely unaffected?""), the unexpected arrival of that larcenous war buddy (""My share kept dwindling""), running rapids in a dinghy, snakes, hostile natives (friendly to Miss F. of course), gun showdowns, discovery of the plane (stuck up in the branches of a forest!). . . plus the usual final betrayals and ironic fadeout. By Kyle's own standards, in fact, the plotting this time is rather uninventive, though highly scenic. The extra appeal lies instead in doughty, implacable Miss F., as viewed with alternate admiration and fury by downbeat narrator George. All in all--a niftily balanced comedy/action adventure.