William Helder, the head of a 300 year old family firm, lives in London in spacious and comfortable apartment above his office, with a magnificent view of the busy River Thames flowing below his windows. His well-off and well-ordered life brings him comfort and satisfaction, while part of his active leisure time provides exercise and variety, and opportunities to indulge in a hobby of his, as he follows clues in his search for a certain silver flagon, an heirloom of his family. A collection of twelve silver flagons had been presented to an ancestor, two centuries ago, by King William and Queen Mary—but through the years some of them had gone missing. All—except one—had by now been recovered. William’s search for the missing flagon leads him along many interesting paths, during which he meets a girl who joins him in the chase, and as they progress together he discovers that the silver flagon is not the only prize he is striving for.