In the story "April 2026: The Long Years," Hathaway builds four robots to represent his wife, son, and daughters after their deaths. With his family buried in a Martian graveyard after an unknown virus takes their lives, Hathaway builds replicas of his dead relatives "with all the power of mind and memory and accuracy of finger and genius."
His genius remains undiscovered until he meets Captain Wilder from the Fourth Expedition (of which he was a crew member) after twenty years. Captain Wilder offers to take Hathaway and his family back to earth, and Hathaway agrees. However, the Captain is shocked to discover that Hathaway's wife, two daughters, and son have not aged since he last saw them. Williamson, a member of Captain Wilder's crew, soon discovers the graves belonging to Hathaway's real family. The Captain and Williamson realize that Hathaway's current family are all robots, built by the lonely man for the sake of his sanity.
Before they can confront him, Hathaway dies of a heart attack. However, before he dies, he begs the Captain not to burden his robot family with news of his death. Meanwhile, Captain Wilder does his best to gently break the news to the robots and is pleasantly surprised to find that the robots exhibit both compassion for Hathaway and affection for their creator. Eventually, the Captain and his crew decide not to switch off the robots' batteries; the Captain muses that the robots have as much right to existence as do humans. So, after bidding the robots goodbye, Captain Wilder and his crew leave for earth.