Mary had a Little Lamb, but now Little Lamb is lost.  Dora and Boots jump into a big book of Nursery Rhymes to bring Little Lamb back to her best friend, Mary.  Along the way to Mary's House, Dora, Boots and Little Lamb pick pickled peppers with Peter Piper, help the Itsy Bitsy Spider climb up the Water Spout, ride a cow over the Moon, put Humpty Dumpty back together again, and even catch a ride in a motorized bath tub.  Rub-a-dub-dub!