Artemis Fowl's mother suffers from a deadly underworld disease. Only a medication made from a special species of lemur can save her. Unfortunately, Artemis himself had the only specimen of this species killed. So, he has no choice but to travel back in time to track down the last descendant of this species. Instead, he first encounters his 10-year-old self, who is reluctant to part with the precious creature. Now it’s Artemis against Artemis. Another underground power, Opal Koboi, is also after the lemur, as it can make her the ruler of the surface world and humanity. A wild chase begins, which the older Artemis wins. He manages to jump into the time tunnel with the lemur in his arms—and his younger self. Together, they will defeat Opal.