When a local down-on-his-luck landowner asks Martin Clay, a young would-be art historian, to value some paintings, Clay suddenly sees the chance of a lifetime: the opportunity to perform a great public service, and at the same time to make his professional reputation - perhaps even rather a lot of money as well. Believing one of the paintings to be a missing masterpiece he hatches a plot to bring the picture into his own possession. As Clay stumbles headlong into the moral and intellectual labyrinth of his own devious plan, things start to go badly out of control...