For only a dollar, Thunder is a terrific bargain. But what does a boy do with a dangerous 2,500-pound buffalo that can break out of any corral ever built? Nathan Riggins has to find some way to keep Thunder from killing someone or being killed. He finally decides to donate his buffalo to the Carson City Zoo. But getting him there will be a problem. Thunder has already destroyed one rail car and damaged the train's engine. The railroad refuses to ship him again. The answer comes in a surprising way.