When helicopter pilot Mike Tempest is fired from his job with a London Air Taxi operator, he's short of cash and excitement alike. Temporary salvation comes in the form of the vivacious but businesslike Miss Bird, who offers him one day's work. Though suspicious of her motives, Tempest accepts but regrets it just as quickly when he finds himself on the wrong side of the law. On the run, but with large rewards in the offing, he embarks on a quest to hunt down the villains himself. Along a trail increasingly bizarre, he encounters spectres from his own past, romance in an unexpected quarter, and a plot far deeper than mere extortion. Could a century-old crime still threaten the destiny of a nation? As Tempest skims stormy waters en route to a climactic ending, he has only a vague idea of how to save a situation that began with just a cappuccino coffee at Tower Bridge.