Greatly atmospheric tale and it involves a horse!
Silver Blaze, the fastest horse in the upcoming Wessox Cup is missing. More so, his trainer is dead. So Holmes and Watson head to Dartmoor to investigate. The solution is simple, the trail leading there not so much, and though I thought I'd figured it out, I didn't.
The famous quote, 'see the value of imagination,' is in this one, which is at odds to how Holmes usually operates, or thinks. (Logic is Holmes' usual mantra.) Plus the even more famous one: 'the curious incident of the dog in the night-time,' which, of course, means the dog was silent, didn't bark, when it should have. (Thus, the 'curious incident.')
Anyhow, a quick and fascinating read, and so far one of my top #5 Holmes stories.