Dick Francis: Twice Shy (1989)

An Irish computer programmer who is also a skilled, amateur mountain climber is murdered when his safety line is cut. Because Cleveland's nephew has been taken in by the dead man and his wife, he is drawn into the case. The Maguffin he is seeking is a computer disc with a program that allows you to pick the winning horse 65% of time, but who has it? Among those whom Cleveland encounters in his search is the beautiful Cassie Donovan, one of the few female horse trainers in Ireland.