- Dr. Hathaway (from the Fourth Expedition) lives all alone on Mars—except for his beautiful family (wife Alice, daughters Marguerite and Susan, son John).
- They missed the rockets going home because they were off doing archeology in the hills.
- Archaeology: the most dangerous science.
- Oh, also, Hathaway has a bad heart, so let's hope he doesn't get too excited about anything in this story.
- There's also a mystery about why Hathaway visits a cemetery with four tombstones. Probably it's a pet cemetery, right?
- One day a rocket comes down to Mars.
- It's Captain Wilder, who we last saw in the Fourth Expedition ("—And The Moon Be Still As Bright").
- Wilder got sent to explore Jupiter so he wouldn't interfere with the colonization of Mars.
- We heard about that first in "The Off Season." Wow, it's almost like these stories are linked together somehow.
- Wilder has been away for 20 years, but he's now going back to Earth because… maybe he's run out of Seinfeld reruns?
- Anyway, he finds Hathaway because Hathaway lights an entire abandoned city on fire to show Wilder where he is.
- Wilder and his crew are happy to meet Hathaway, though it's a little weird that Hathaway is so old and his family is so young.
- During a celebration breakfast, Wilder sends his crewman Williamson off to investigate the cemetery, where he discovers that the four tombstones are for . . . Alice, Marguerite, Susan, and John!
- So who are these people pretending to be Hathaway's family?
- Robots. (Cue the scary music.)
- Hathaway dies and is buried in the family cemetery.
- Wilder talks to Alice about how she's a very loving robot and how Hathaway survived all these years by pretending that he wasn't alone.
- Wilder takes his rocket back to Earth but leaves the robots on Mars.
- The robots go on living—er, existing?—either figuring out better ways to build cars or better ways to beat people at Jeopardy!