This is one of the better novels from Dick Francis. Like a few of the others in the series, this one is only loosely set in the world of horseracing, and the protagonist, Tony Beach, is not a jockey but rather a wine merchant. He owns a small shop and has spent the last six months grieving for his wife who built up the shop with him and then died of an aneurysm while six months pregnant.
Beach is simply going through the motions of living, opening his store, dealing with customers and occasionally supplying the liquor for various parties. On a Sunday afternoon, he's catering the liquor for a party thrown by a successful horse trainer. A lot of important guests have gathered for the event, which is being held in a large tent on the grounds of the trainer's home.
As the party gets under way, the trainer's principal assistant approaches Beach with a problem. One of the owners who has several horses with the trainer also owns a restaurant. The trainer and his assistant had dinner there recently as guests of the restaurant owner. The assistant is concerned because he believes that someone is fiddling with the liquor served at the restaurant. The man ordered an expensive Scotch whisky after dinner, but was served something decidedly inferior that had apparently been substituted for the whisky that was supposed to be in the bottle.
The assistant fears that someone may be cheating the restaurant owner, and he asks Beach if he would be willing to go to the restaurant and order the whisky to confirm his suspicions. Then he can delicately approach the owner and inform him of the problem. However, as they are discussing the matter, a horse van breaks loose, apparently accidentally, rolls down a long hill, and smashes into the tent where the party is being held, killing a few guests and injuring others. Among the dead is the restaurant owner.
Beach now finds himself assisting a firm of investigators, and the police as well, in a wide-ranging investigation involving mislabeled wine and spirits. It turns out to be a very dangerous assignment, given that there are some powerful adversaries who will stop at nothing to protect the racket they've perfected.
Readers will recognize Tony Beach as a typical Francis protagonist--apparently quiet and unassuming, but underneath the mild exterior, a man who is smart and tough as nails when the going gets rough. The plot moves along well, and the details of the liquor business that one picks up along the way are interesting too. All in all, a pleasant way to spend an evening.