The self-replicating spacecraft are named "Gaijin" (Japanese for "foreigner"), after their discovery by a Japanese observer on the Moon. Malenfant travels in a prototype fusion engine to the Kirkwood Gap and discovers an interstellar teleportation device. He travels around the galaxy to uncover information about the Fermi paradox (see below). At the same time, the story also follows the efforts of Humans on Earth and the eventual draining of the Earth's resources, making a move off-world necessary. At the same time small group of humans use anti-aging techniques and an alien form of interstellar teleportation to "parachute" in on the changing solar system over many centuries.