The Archduke has organised a party to honour the Knights for their service to the city. Leicester and Nick have been given guard duty for that night over the artefacts at the cathedral which the Knights are supposed to protect. Leicester sees a great sword known as the Sacred Celestine and feels particularly attracted to it, fascinated in its construction by the ancients. The Tortillas have been given guard duty outside the Archduke's palace, and as the party is going on, they are attacked by a crystal monster that seems to have the shape of a serpent. It can move so quickly when it attacks that its movements cannot be seen, so much so that no one can hit it. Minette summons Garnet who is sent to call for Leicester at the cathedral, and when he finally arrives he realises that the monster is attracted by light, so he uses a strong crystal-powered lamp to attract it and allow Chelsea to destroy it. How or why the monster could have appeared in the middle of the city is a mystery.