In this adventure for Exiled in Eris, the characters are hired by a noted scholar. They are to accompany him on an expedition into the heart of Eris to find and explore what he believes to be a lost Aeonian city, rendered invisible by a powerful artifact. The story then follows the journey over the desert by airship, a visit to the small Erisian town of Sweetwater, a perilous overland trek, a surprise ambush in the middle of the night, the exploration of the ancient ruins of the invisible city, and the dangers that lurk therein. Unlock the forgotten secrets of the aeons in City in the Mirage.