In the third book, "The Eternity Code", Artemis (in what he considers to be his last criminal act before his father recovers from his injuries) creates the C Cube, a mini super-computer based on the People's technology that is decades ahead of human technology. He plans to make a deal with Chicago technology businessman Jon Spiro over the Cube, but Spiro double-crosses Artemis, steals the Cube, and wounds Domovoi Butler in the process. Along with Holly Short and Foaly, Artemis succeeds in healing Butler and ensuring that Spiro does not discover the existence of the People through use of the C Cube. The C Cube is recovered, with the help of Foaly, Holly, Juliet (Butler's sister), and Mulch. But to gain the help of Foaly, Holly, and their Fairy technology, Artemis has to agree to Butler's, Juliet's and his own memories being wiped by the People, to avoid future misadventures. This happens at the end of the book.