Blood Sport
Dick Francis Audio Book

Gene Hawkins, investigator by trade, was expert at arranging events so that they appeared accidental to all involved. Therefore, when he himself witnessed an 'accident' his curiosity flared up bright, and he insisted on looking into what he regarded as a work of art. A quarter of a million pounds worth of Derby-winning stallion had vanished into the Blue Grass of Kentucky... and a young man and a girl spent a dangerous afternoon in a punt on the River Thames.
From these far-apart but related beginnings, Gene Hawkins found himself trailing lost blood-horses over half of America, until he in turn becomes the prey.