I Capture the Castle guests describe each other in terms of famous artists. Topaz is called a work by William Blake, Rose is said to resemble Emma, Lady Hamilton, the muse of the painter George Romney, Simon says that Cassandra is like "Girl with a Mousetrap," a painting by Joshua Reynolds, and Mrs Fox-Cotton is said to be a work by Salvador Dalí "with snakes coming out of her ears". Simon introduces Cassandra to the works of Claude Debussy: "Clair de lune", "La cathédrale engloutie", "La terrasse des audiences du clair de lune". She also listens to J. S. Bach's "Sheep May Safely Graze"
The Secret of the Selenites gusts of wind; the fleet-footed Cavallo; and Hercules, who is a strong as his namesake. They board a tall-masted ship, the "Clair de Lune", and deliberately sail into a fierce storm. By inflating a trio of hot air balloons and riding a waterspout high into the air, the ship takes flight and leaves Earth. Arriving at the moon, the "Clair de Lune" descends into a lunar crater where it becomes wedged. The adventurers fall into an underground lake and are attacked by swimming monsters, but are rescued by flying creatures and soon meet the Selenites, who are humanoid but have