Only for Yellowstone Kelly can a lazy day at the bar turn into a race against time to recover a priceless skeleton Charles Darwin's survey aboard the HMS Beagle forever changed natural history, causing a flurry of wild speculation and exploration in the wake of every major find. Yellowstone Kelly, fresh off his misadventures in Kelly Blue , is cooling his heels in a Wyoming saloon when he encounters a specimen hunter. Pignuts, the saloon owner, had bartered whiskey for a strange, three-toed horse skeleton and now displays the fossil proudly in his bar. A cold-eyed stranger comes in, buys the bones for a handful of gold, and introduces himself as paleontologist Jonathan Cope. Cope recruits Kelly to be his guide through the Wyoming wilds. The professor and his beautiful assistant, Alys, hope to find what the Sioux call Thunder Horses—enormous fossilized bones weathered out of the hills. This trip, like many other Kelly expeditions, won't be an easy one. Trailing the trio on their journey is Blue Fox, a Dartmouth-educated Cheyenne madman who notoriously loathes professors of all stripes. Along the way, Kelly crosses paths with some of the most illustrious figures of the era as he helps his group navigate the many predicaments of the Old West.