According to myth, cats have nine lives, and Alexander Catt II (also known as Lexi) has spent his former lives with scientists of medicine throughout history. In these adventures, Lexi witnesses medical breakthroughs and discoveries, and learns the value of hard work and integrity. In Lexi and Marie Curie Save Lives and Limbs in World War I, Lexi lives in France with the Curie family at the beginning of the 20th century. When injured soldiers return from the warfront, Marie realizes the need for x-ray services, and sets to work providing these to the doctors at the front. In doing so, she saves countless lives and limbs.