Most of Singularity takes place in the rural town of Sushan, Illinois in and around the former home of Ambrose Kittery, as well as in "the playhouse" built in the meadow behind it. The main house is typically Gothic, jammed with antiques, old furniture, books, an Illustration by Michael Hays for Singularity by William Sleator. Dutton: New York (1985).

old-fashioned and decaying bathroom and kitchen, and carefully mounted skeletons of some unusual creatures (like a "cat" with six legs). To Harry and Barry Kresner, twin brothers who watch the house after their parents inherit it, staying there is an adventure. The house is very remote and there is no one around to tell the boys what to do.

Soon after their arrival, Harry and Barry find a meadow behind the house with a sundial and a playhouse, "a nondescript rectangular building with a sloping roof, about twelve feet long...