One by one, various base systems—gravity, climate control, and ultimately the food dispensary—begin to shut down. Lucas is injured during the storehouse construction project and, after the householders have an apparent argument concerning him, is given a sedative. He awakes to find himself in an empty house and steps outside in time to hear the roar of an onrushing wall of water, which lifts the storehouse off its foundations (incredibly, without damaging it) and threatens to sweep Lucas to his death. But then Lucas finds himself back on the base, in time to watch its crew destroy one another in mutiny, mayhem, murder, human sacrifice, and the eventual suicide of the base commander, who is the crew's last survivor. Following this, Lucas experiences an attack of vertigo. In fact the simulator machine has run its program, sounds three piercing alarm tones, and ejects him into the waiting arms of Shepherd just as the crew of Apollo 20 arrive to rescue them. That rescue is just in time—because after Apollo 20 completes trans-Earth injection, the self-destruct sequence runs its course, and the base destroys itself, apparently in a thermonuclear detonation. Back on Earth, the mission commander studies the Bible—and realizes that he actually witnessed the Noachic Flood and even ate at Noah's table. Also, the base builders never attacked Earth, because they were from Earth originally—from Antediluvian Earth. He and Shepherd further realize that God has entrusted him with a warning, which he must convey to anyone who will listen. The novel ends when it shifts to somewhere on the surface of Mars, where another base similar to the one found on the Moon, ominously activates by itself. History of Project Apollo, Bible history (specifically of Noah and the Great Flood that bears his name), speculation on the nature of Antediluvian civilization, the utility of prayer, and the Providential nature of God. "Ice" highlights the Christianity of many Apollo astronauts (one of them wrote the foreword to this work). It touches on several themes at once: the history of Project Apollo, how the nation would have handled what would have been an appallingly demoralizing disaster, the possibility of extraterrestrial visitation of the earth in modern or ancient times, and speculation about the Flood. "Ice" attracted little notice beyond the Christian readership to which Johnson directed it, and it is now out-of-print. She had intended a sequel to this novel, titled "Fire", based on a similar encounter on the planet Mars.