In the spirit of
Edwin Abbott Abbott's
Flatland, Dewdney and his computer science students simulate a two-dimensional world with a complex
ecosystem. To their surprise, they find their artificial 2D universe has somehow accidentally become a means of communication with an actual 2D world: Arde. They make a sort of "
telepathic" contact with "YNDRD", referred to by the students as Yendred, a highly philosophical Ardean, as he begins a journey across the western half, Punizla, of the single continent Ajem Kollosh to learn more about the spiritual beliefs of the people of the East, Vanizla. Yendred mistakes Dewdney's class for "spirits" and takes great interest in communicating with them. The students and narrator communicate with Yendred by typing on the keyboard; Yendred's answers appear on the computer's printout. The name Yendred (or "Yendwed", as pronounced by one of the students, who has a speech impediment) is simply "Dewdney" reversed. Written as a
travelogue, Yendred's journey through the West takes him through several cities. He visits the Punizlan Institute for Technology and Science, where Arde's technology is explored in great detail. For example, all houses are underground, so as not to be demolished by the periodic 2D rivers; nails are useless for attaching two objects, so tape and glue are used instead; most Ardean creatures cannot have
deuterostomic digestive tracts since they would split into two; even games such as
Go have one-dimensional analogues such as Alak. An appendix explains various other aspects of two-dimensional science and technology which could not fit into the main story. The underlying allegory culminates in Yendred's arrival at the watershed of the continent and the planet's only building above ground, where he at last finds Drabk, an Ardean who professes "knowledge of the Beyond" and teaches Yendred to fly. Yendred finds that it is no longer beneficial to maintain contact with Earth, and contact with Arde is lost. ==Development==