Tilly meets Nimród, the extremely smart and skillful pony, at a circus performance. He is overjoyed to learn that the special horse will be staying at the Silver Horseshoe farm for a while as his rider, Clara, joins another circus troupe. Tilly can't wait to find out what stunts Nimrod is capable of. But the mischievous pony comes up with surprises that the little girl didn't expect at all.