The story is set in the near future, when the Moon is colonized with people living in underground cities. The "menace" of the title is a glamorous woman tourist who visits the Moon colony. She is assigned a young guide named Holly, a 15-year-old girl and aspiring starship designer who is the first-person narrator. Holly's best friend Jeff develops a crush on the "groundhog" visitor, Ariel. As Jeff spends more time with Ariel, Holly becomes jealous and begins to doubt his friendship.